I've got tons of stuff compiled but here's a brief explanation of the basics to get you started. If you want to get a game going definitely let me know- I've never played for rankings and its been a few months but i could still teach you a thing or two probably.
Couple of tips- as a merc: Listen-amp up the sound. Your partner makes no sound. Stay away from railings
Keep mines close to you as a shield for blind spots... but far enough away so that you won't get hit by the explosion. Mine and trap high traffic areas, not near nodes.
USE all types of vision, don't be afraid to use your laser either.
Try to find spies where you would hide if you were a spy.
Think like a spy... Example: if a spy is low on health because he took some fire, where is he going to go? Medi kit. ALWAYS think like a spy... I cannot stress this enough.
Use your melee attack in thin air for the speed boost...
Keep your back against the wall when possible flick on motion and lasers from time to time to track moving and still foes in darkness.
Listen and Watch (Electro vision) for sticky cam... This is makes all the difference in the world. And in turn WAKE your partner up. Also when being shot at, use electro specs.
Use laser to check identity. Tazer then leave them a bit to waste counter time.
Flares are plentiful and refillable at ammo pots- use them over the headlamp.
Use mines and traps in loud ambient noised areas.
Ambush- don’t chase. Spies run about twice as fast as you.
Charge thru smoke grenades so they cant block off areas. Then jump or crouch to avoid neck snaps.
Plant mines- let spies see them and then recover and move them. Makes them weary, confused.
Spies: Be confident, Don't be afraid if your in the dark... just because a merc is close to you... doesn't mean he can't see you.
Don't freak out if you start taking fire, ie running around throwing smoke grenades everywhere, run back to a medical kit if possible.
Move slow (often) Move quick if the situation provides, IE, you are aware of all mine locations, or mercs are down.
Sticky cam entrances that you know mercs are headed for
Use spy bullets on doors and merc friendly regions or on node paths for early warnings.
Chaff grenade is hardcore, disable lights disable merc extra vision modes... I always have this on quick use,

the smoke and flash combo, flash doesn't work on a merc that has motion on.
Use the Roll manuever when the need to move quickly calls.
DO NOT MOVE THE STICKY CAM, fire it and wait- its very noisy.
USE your Tazer Constantly, If one spy is hacking the ND this alone can buy the time to geter done.
Make mercs empty a clip at you and then chaff them so they cant reload.
Spy bullet areas you want to know about like radar. Use noise makers to attract mercs.
Flash then smoke combo confuses then chokes.
Smoke then chaff disables and deafens.
Flick electro specs in high traffic areas, never use nv goggles-you should know the map.
KO mercs then jump them or haul ass. Killing them just gives them more stuff.
Code words for when you are being listened to. Label nodes as Numerical points-not locations or room numbers.
Playing as the Spy:
-while running towards a wall, double tap "Y" just before you reach it in order to perform the wall run. This will make the spy sprint up the wall in front of you. If there is a ledge above you he'll grab onto it and you can then pull yourself up. If there's no ledge he will do a backwards summersault off the wall. Some people have questioned the usefulness of this second maneuver. If you are able to do it just right you can kick off the wall and land on the head of a perusing merc. This will kill the merc and make you look like a total

ing bad ass.
-Spy cams can be used as offensive weapons. Don't think of them as cameras that you can use for reconnaissance. Think of them as tiny gas bullets that you can launch at patrolling mercs. Fire one at a merc and quickly hit the "A" button to release the gas.
-Shocking the mercs is always fun but try aiming for their face. A direct head shot with your shock rifle will actually short out their helmet and turn off their HUD. For the merc this means he loses his radar, his ammo and health indicators along with the ability to see the status of any capture points or alarms. It's super disorienting and it takes a while for the helmet to reset itself.
-When you have a merc in a choke hold you can talk to them by holding down the white button. This is fun but a better strategy is to knock them out (right shoulder button) or snap their neck (A button) as quick as you can. The reason is that a talented merc will yell out to his partner the second he's been grabbed and alert him to his location. You don't want to give them the time to do this. As to whether you should snap their neck or just nock them out, well each one has it's advantages. If you kill a merc, he will re-spawn again with all his mines and gear. This makes your job more difficult since now you need to deal with even more defense. There are certainly times when killing him is the right move but think strategically. Sometimes a little nap is all they need.
-Your different vision modes are useful but don't rely on them too much. A smart merc who uses his EMF mode will see you coming from a mile away. The EMF tracking mode can pick you up even through ceilings, thin walls or vents. Use your vision modes in short bursts. On and then off again real quick is the key to staying hidden. If you see a merc's visor go blue that means he has switched to EMF mode. Your best bet is to go totally dark and not use any of your gear until he passes.
-The most important thing though is communication with your teammate. You really need to coordinate your attacks and work together. Try setting it up so that you are both disarming different bombs at the same exact time. Cause distractions to take some heat off your teammate if he is in a tight spot. By firing an alarm snare at one of the many sensors in each level you can trigger an alarm without exposing yourself to any real danger.
Dont use vision modes if there's a merc looking in your direction. If he's looking away switch to thermal to get a sense of what spy devices have been placed in the area(they show up on thermal). Then quickly switch back to normal.
If a merc knows you're around, but has no idea where, shock him with your gun, then place a spy bullet on him(or just spybullet, depends on your aim). Now you know where he is, just about all the time.
If it looks like you can climb it, you probably can. And should.
Always disable spytraps when you find them(quick flip to thermal every time you enter a new area to look for them and bombs). Unless you're trying to draw attention, in which case trip them and run
(hospital level)
Shoot through the lasers at the door, or window. Then take up position inside the room and hide. The mercs will sweep the area, then move on. If they dont see any lasers broken the next time you make your move(which means shooting out the motion sensor) they'll probably head to the other room without noticing you until you start decomtaminating(broken lasers = SPY ARE HERE!, no broken lasers = spy somewhere else?).
If you know they keep sectors, trip a sensor and set up a trap for the guy covering your area. Trip the sensor, and take up position above the door to the room you're in. Shoot a spy cam a little inside(where it wont stand out because of the light from the hall) and leave it pointing at the door. Dont move it, or it'll give the game away. When the merc runs/grenades/whatevers his way in, be like "here, have some gas" then go get the node.
THE MERC
-Try to mix up the kinds of mines you use. Throw in more laser mines whenever possible. A good trick is to place a laser mine at eye level directly above the terminal. A spy will see it and crouch in order to sneak up on the device. However when he starts to deactivate it he will automatically stand up, breaking the laser and blowing himself up.
-Don't place your mines directly on the devices. Instead place mines along the paths that you think the spies will take in order to reach the devices.
-If a spy drops a smoke grenade in front of you switch to motion tracking. Also use the "A" button while moving forward to charge through the smoke. By charging you can get through a pocket of smoke without passing out.
-During close range combat switch to motion tracking. This will help you keep track of the spy and make sure he doesn't get around behind you. Also, the spy's flash bangs have no effect on you when you are using one of your enhanced vision modes. Also switch to your tazer since grenades at this range are useless.
-If you happen to see a spy choking your partner you can zoom in and deliver a head shot to the spy and kill him. It's a tricky maneuver but it can be done.
-You and your partner should each have certain points that are your responsibility. For instance, in the Hospital one Merc should watch the upstairs while the other guards the bottom floor. Stay in constant communication. Always keep your partner informed about your situation. Do you have a spy on your floor? Do you know for a fact that both spies are on your floor? Did you see a spy run towards your partner's floor? This is the sort of information you need to constantly be sharing with your teammate.
-It is important to understand how the "hearing" works as merc. Your targeting reticle is broken up into four quadrants that can be lit up as well as have an arrow placed over them. A glowing quadrant is telling you what floor you hear something on while the arrow is telling you what direction. Let's say for example that on your reticle you see the upper quadrant light up and an arrow appears in the bottom quadrant. This tells you that you are hearing something behind you, on the floor above you. Be sure and alert your teammate to noises you hear coming from his floors. Also take note that you cannot "hear" anything when using the laser.
-If you're grabbed by a spy your first instinct needs to be to call out your position to your teammate. No matter what kind of bullshit the spy is whispering into your ear you need to alert your partner of exactly where you are and what's about to go down.
-It is important to have a solid understanding of each level from the point of view of the spy. The better you understand the various routes in and out of a map the better you can defend those points.
when Merc, make good use of your noise detector. It's 10x more useful than your vision modes, and has saved my life hundreds of times. As a spy, teamwork teamwork teamwork. With Merc you only need a loose understanding of where your partner is and what area he patrols, with good division of resources(mines, spy traps). With Spy you gotta have your partner covered at all times.
For example, when my partner starts hacking a terminal, I shock and throw smokes around both mercs, and go in to get one by the neck. Always have either flash and smoke grenades, or chaffs and smoke. Chaff if you're doing a level with many lasers, smoke for any other. You may even want to consider having all three, though I like to have the 2 grenades, spy bullet or alarm snare(it's

ing freaky being a merc and having sound pour from every direction, not knowing where to look), and sticky cam. Sticky cam's a beast.
Remember, just because you're a merc, doesn't mean you can't set up ambushes. Hide around a corner or on the other side of a door if you know the spy is going for an NDI33.
learn all the levels like the back of your hand. knowing where to run when you are seen is really important... and always shock and camera sleep them, that just

s with them and they get paranoid
nother good thing, if you know theres a spy somewhere and you dont need the torchlight... hold down B for a bit ans you go into sniper view, if you shoot him in the head with 1 bullet he dies. 2 times to the chest he dies. mercs are

ing bastards if you know how to use them efficiently
1) never walk on a ceiling with you visor on. If a well skilled merc is in the same building and/or room they will see you everytime.
2) this is a move alot of spies use against me, when you are faced with a merc charging, drop a smoke nade then a flash bang. If done correctly, the last thing the merc will see is a cloud of smoke. Some players feel that this a cheep move, but it does work.
3) moving crouch and very slow will allow you to not only disable mines but pass right by a merc with his motion tracker on.