I use thunderbolts alot, and my tactic is usually to float around the top of the map, cut my throttle and dive where I think some enemies are. Having my throttle cut means I don't fall that fast, so I have plenty of time to find a target. All of this so far being done while passive, if I find a slow or stationary target, I will dumbfire my narc and if it hits I ping my radar long enough to fire my missiles so will home in on the narc, this way I minimize my exposure as much as possible. If i'm lucky, i'll find a target quickly and narc and fire before I hit 900 meters, and if it or no other enemies start shooting at, I can pull up and make a second pass before my narc wears off. If baddies do start firing at me, i'll keep diving and use the terrain for cover.
I can even attack AA tanks this way if they're not already scanning the skies looking for me. Longtom tanks are usually an easy kill too, as they usually die in 2 salvos of thunderbolts.
To be honest i'm pretty terrible with firebombs. I just can't seem to ever hit consistently with them, so whenever I decide to play aero on a map, I usually end up playing the thunderbolt Sulla the whole game.
EDIT: grammar.