chopper gunner tips, often overlooked is the first tip.
drives me mad when i am trying to approach a target without being spotted, and the chopper gunner spawns in and is like "OMGZ CHPPR GUNNAZZZZ!!! " and just wildly starts firing at the sky, the floor, tries to shoot someone from one side of the map to the other. not only does he give away your position, he also wastes ammo which takes a while to replenish which is another tip that some people might not have realised. in bf3 ammo was unlimited in vehicles. in bf4, it is technically unlimited, but you have a "reserve" which fills back up very slowly. for example, a tank or a chopper might have one round/set of rockets in the chamber, and 5 in "reserve". once the 5 have gone, they will fill back up much more slowly. this is pretty important in tanks, where tit for tat shelling can mean you are dead if you have already used 3 shells to try and snipe a recon , and only have 3 shells left to use immedialty before you have to wait for a long reload/replenish