This is a very very basic guide to survive in battle. Anyone who had played with me knows that I tends to survive when I wanted to, like our whole squad wiped out and I am still left alive there.
1. Nothing could really stops you from dying
The moment you spawn, you risk dying. The best way not to die is not to spawn.
You might try to keep spawning at a flag that is under constant bombardment and enemy fire. You'll die a lot, a lot, you'll complain of spawn raping, but that doesn't stop you from dying most of the time. Spawn somewhere else and organized a come-back, let's say, to grab a tank and surprise those camping buggers from behind or side, or man a certain artillery piece and blow those campers to hell, both are relatively less risky than to spawn again at that same place. Else, enjoy your horrible K/D ratio.
2. You don't get fired at for no reason
When you hear gunfire, when you hear bullets impacting near you, usually that isn't a good thing. There are chances that it is your reckless teammate thinking you are an enemy, but that is usually not the case, and even if it is the case, you still got to take cover.
When someone shoot at you, it means he saw you, and wanted to kill you. My very humble advice is not to pop your head up from the cover you disappeared into, as that is where his ironsights would be pointing at. Crawl to somewhere else to counter-fire. Or just run away if you cannot win or do any harm.
A good way to get away is to throw a grenade from cover, or whatever to deceive them that you are planning to strike back from the same position like popping your head for a split second to make them nervous. Then run away like hell.
Another situation is a mortar or artillery shell exploding near you. Chance are that you got caught in the artillery spot: the gunner sees you and want a free kill! Most of the time it is very unwise to get out of cover if you cannot run away fast enough from the spot - you'll just be blown to pieces when the next shell drops.
3. Don't shoot unless you have a good reason to do so
noise, noise attract attention, death messages make people furious. Yeah, sometimes you decided to go for that one lousy infantry, yes, you killed him, but you lost your AT gun to a random bazooka. Most of the time, an impatient, reckless player only gets 1:1 K/D ratio as that guy is the only kill that had before dying.
Remember that the kill messages and gun noise are perfect way to locate a certain player's location. If you are deemed a threat, or sometimes simply a free kill. You'll die quite meaninglessly.
Let's say my way to use AT gun would not include firing at a lone soldier that your teammates could easily take care of. If they didn't realize your presence, it is a good idea to wait for the entire enemy squad to show before firing. That way you have a chance of wiping out the entire squad and they won't be able to retaliate that easily.
If you cannot cap a flag, killing that poor loner asking for artillery spots near the flag is a very bad idea. You didn't contribute anything to your team other than making a useless guy rage. Wait for a better opportunity or a more juicy target.
4. Don't be reckless, this is not CoD
FH2 is not about pressing W at the enemy's direction and just keep clicking your LMB on an enemy. Chance are that you'd just keep dying that way. Running through an open field, or trying to stop your truck at an enemy position without cover is 99% suicidal. It is usually too late to regret of your recklessness when you saw the muzzle flash of that MG gunner, or a yellow rocket flying to you.
Patience is really important, waiting 2 minutes for the Tiger to look at somewhere else could earn you a chance of busting him and contribute to your team rather than dying again meaninglessly pressing W at Tiger after respawn.
If you have patience, teamwork is easy. And teamwork is the essence to survive - in any situation it is better to have 5 other guys to be a potential target under your enemy's ironsights or it is just you being aimed at by 6 guys? Your team could also deal with a much wider range of enemies so you don't need to use your pistol to fight with rifles or MG to fight with tanks.
In a war, or in this case, FH2, someone has to die. But dying without having a chance is really bad. Just make sure this guide helps you survive well and save a ticket for your team.