If you are new, read this. If you are vet that plays like a new guy, read this lol:
So you've spawned into the game world. Probably as infantry first, hopefully at an action filled battle at a forward spawn point. Things to not do: Don't stand there shooting into the air to test your weapon, don't throw smoke at your team mates, don't wander around aimlessly.
Things to do: Get some cover first. Even inside the spawn point is good. Bring up your map and orientate yourself. Find the town you are attacking on the map, find the depot's capture point (CP) you are supposed to try to capture. Once you've found that, there's several options. You can try to solo capture it, which is not recommended, since solo captures take a lot longer. You can wait for team mates to help you, which is the best way since it will be much faster, or you can pick a spot to defend the FMS (the thing you just spawned from). Defending the FMS is good, since hardly anyone does it, and within a few minutes the enemy will come to you since they want to destroy it.
If you want to defend the FMS, there are several things you can do: Use infantry, since enemy infantry will the the major threat to destroy it. Use an anti-tank gun, since enemy tanks will seek to camp it. Use an AA gun, since enemy bombers are also capable to destroying your FMS, but less likely. Which ever you choose, move away from the FMS. Defending it point blank will just get you killed by the enemy coming to kill you. If AA (anti air) or ATG (anti tank), move at least 200m behind (away from town usually) and pick something that gives you clear lines of fire around the FMS but also gives you some cover/concealment. If you pick infantry, you can stay closer, since enemy infantry (EI) will be harder to spot than a tank/plane.
If you happen to spawn at one of your FBs (forward base/fire base), you have to figure out what you want to do: Attack the objective or defend the FB. Defending the FB can be boring, since you don't know if the enemy will come to destroy it or not. Again, you can use infantry or tanks or AA/AT guns. Same thought process applies: Don't sit right at the spawns to defend them, move away to a better spot. Especially if you are using AA guns, NEVER EVER set up in front of the vehicle spawn, the enemy bombs that with alarming regularity, and you will just die.
If you spawn a tank and want to get to town to attack, do yourself a favor and don't use the road. It's a death trap usually, and you'll end up dead and on fire. If you must use the road, make sure someone else is in front of you so they die first LOL.
Also, the BEST thing you can do is communicate with your team. Either through ingame chat, or voice comms. Ask for help, call out enemies when you see OR hear them, mark them on the map, etc. Help your team, don't be a detriment by wandering around deaf and blind and dying lol.