Take advantage of armored vehicles.
Everyone has been talking about small arms, but forget the big stuff. Its important for armored vehicles to stay away from close combat zones and use long range shots. Jungle areas are one exception where you want to keep rolling. Avoid antitank mines by following the Stop, drop and roll. Stop at the water, drop your shells to check for mines, and roll your tank around blasting away tree lines and killing enemies.
There are light armor and heavy armor tanks. Always aim for their rear or sides to do more damage. Keep in mind in a light tank vs heavy tank situation, the light can win if equipped with alternate fire perk which gives you a rocket launcher. One reason I love using Bradleys are due to high rate of fire and faster mobility. Equipped with a rocket launcher and Bradleys can compete with Heavy Armor.
For heavy tanks, I found using the armor perk was more beneficial compared to alternate fire perk which gives secondary machine gun. Enemies will have to fire an additional missile to counter the armor perk.
Whether it is a chopper or tank, use your F1, F2, F3, etc keys to switch positions without leaving your vehicle. Many times the pilot will bail out even when the chopper is fine, or they get sniped. You can take over the seat by pressing F1. If your high enough in the air, you can also get 0.5 to 1 second hang time to quickly switch over to a gunning position before returning to your pilot seat. I always use smoke perk for air vehicles.
Then there are those light vehicles that aren't tanks. In big maps I use them to run people over or place C4 charges and pull a Bruce Willis and jump off as I blow the charges. Or maybe you can pull a Jack Bauer and pilot a UAV mowing down infantry with your blades and rearing blackhawks or apaches causing them to explode. Then again you can be really ninja and drive an ATV armed with C4 into an enemy base, drive it towards their UAV station or enemy, jump off and hop into their most valuable vehicle within 10 seconds before you self-implode the vehicle and yourself.
Its BC2, use the vehicles and make your enemies :cursing: and your teammates :cursing: and you :lol: which is what matters most.