Ok, this is what you do -
To attack a planet, bring in a heap of fighters and small ships, and have your capital ships hang back. Harry theirr bigger ships then, once they are distracted a tad, bring the capitals around the side or just keep your capital ships in abit and cover fire.
My defence is merely this, keep your big ships back near the planet and hold them busy as much as possible with your fighters (which will probably be destroyed, try cover them abit with biger ships) while your orbital ion cannons and turbolasers on the ground help pick em off.
Tada - a strat that prolly will prove ineffective ingame but sounds gud from what we know lol