With this game, you either love it or hate it. I loved it and from what I can tell, most people who hate it are the people who run into the middle of the enemy's camp and wonder why they die so quickly.
Here's a few tips on how to survive and make the game easier overall:
Play most of the game during the night, the enemies visibility falls dramatically. During the day, you can be hiding in the grass and be shot from who knows where. During the night, you can almost walk up to a guy's face and he won't start attacking you.
My favorite combo was the sniper rifle and silent pistol. Use the sniper rifle to clear out as many as you can from a distance and then use the silent pistol to clean everyone up without alerting whoever is still alive.
Never drive in anything besides a jeep with a weapon attached to it. That way, if you see someone coming, it's a quick move to the weapon and you can

them up pretty quickly. Also, try to avoid the roads when you're driving, you can avoid a lot of people that way as well.
You should be saving frequently and also, make it a point to replace your guns at the armory whenever it's easy to. Use the bus stops almost every time as they make traveling waaay more convenient.