If worse comes to worse and you have to use one, first make sure no teammates are flying nearby. 99% of the time the missles will hit them instead. The best way to shoot down hostile aircraft is if their tail is facing you (meaning they are going away from you). Missles like to look onto engine exhausts. Obviously wait for them to pop flares before firing. Shoot your 2nd missle immediatly after the 1st hits, the quicker you run out is the quicker you'll reload if neccessary. The minigun is the best option of all the AA guns, when you use the Phalanx gun on the Essex carrier, be sure to lead your target. If people find out you're there, use the 2nd gun over by the radar and UAV.