[quote name='Failure Online']Does anybody have some general tips for me? The best I've ever done is like 17 and 9. I seem to always get killed a lot. Maybe I just need more practice, but I want to hear what you guys think I should do.[/QUOTE]
Find a gun you like and can control (Combat training!), use it in most of your classes. In fact, play lots of Combat Training, starting on Regular difficulty with even teams. Once you get warmed up and start kicking ass, up it to Hardened (never Veteran, which is suicide unless you're absolutely on your game). Once you're doing decent on Hardened, you should be set to move on to multiplayer, no problem (except lag).
A general tip for [more] survivability is to stick to the outside of the map. If you go through the middle, you should have a plan, or you'll more easily be outgunned/surprised. Also, to know the maps. (Combat training!) - The bots follow most routes that humans would normally take, but not all of them.
Get used to the aim assist (Why aren't you playing combat training yet?), and then used to adjusting to it when aiming down sights. It can sometimes screw up and veer off if you're ADS and the enemy moves slightly.
I highly recommend playing a couple rounds of Combat Training, before going online. (any day)- It can help you mentally prepare for a real game.