1. When attacking a territory that your Missile Base is firing at, there is a little "explosion" icon on the ground target it is aiming at. Drop your bombs/rockets on another ground target so you don't waste your ordinance on a GT that will be totally destroyed anyway.
2. If you are attacking an enemy held territory with or less than 20 capture points remaining, ramming an enemy plane (not an Air Defense Aircraft) is not a bad idea. Attacking planes get 60pts per ENEMY aircraft (not ADA) while a defending ENEMY aircraft gets only 40pts. I'm not saying to go out and try to ram every time but sometimes the situation may call for it and can win you the game.
3. A) If there is an enemy bomber formation about to attack your territory,
B) you can't reach them in time/altitude,
C) there are enemy planes in your territory,
Wait for the bombers to drop their bombs THEN destroy the enemy plane in your territory. Doing this will negate some of their capture points and hopefully keep the territory in your team's hands for at least another bombing run. If your territory has all its capture points, destroying an enemy plane does nothing to increase the capture points but if you can wait until they drop their bombs you can replenish some points so that the bombers don't cap on that run.
4. If you just lost a territory and there are enemy planes still in it (esp. on low health), wait until the 20sec respawn is done THEN shoot them down! I see a lot of "blue" planes shoot down "red" planes seconds after red planes just capped, if you just wait a few more seconds you can start to recapture the territory.