there's a lot to do except blasting orbital cities, which won't work.
i know when i played frontier the first time, i thought what else should these huge weapons be good for? but it's been a long time since i mounted a lpa to my ship. 20mw even if i have more space on a courier are far enough, if you take a 4mw to your courier you can add legally so many shields to your ship that it will bounce back from the bases poles undamaged (or another ship, looks funny when you see a courier in kamikaze manner attacking you is getting bounced straightwards back). small ships you can ignore then, they get roasted like moths on a lamp (still you have to check your shields sometimes, many bounces you can't stand).
but the courier is not the best choice for military missions, especially because you can't scoop fuel and the range of the fixed hyperspace drive is a bit to short.
also if you like to do some assasination between photo/bombing you would like to change the ship because she's to slow (hyperdrive range).
an asp with a military drive three, is a very good choice for the beginning, only missions to planets far out you have to be careful, because you might run out of fuel, and often there's no starport to refuel. still it's a very versatile ship.
but by the risk that i repeat myself, constrictor, but a cobra mk1 is also a good choice even when you need a little longer to scramble up all enemies with a 1mw laser. best choice for assasinations, you get them all, i swear.
something for the sturmovik fans; a cobra mk3 with a military drive and a 4mw gun, i wonder what ship could beat this.
my most loved ship is a gold/black or green/black spotted tiger, looks great! but no real combat ship at least (it might be suitable for bombing/photo if you use old fe2 with wormholebug) and you have to search a lifetime for one (if they still apear in this design in ffe at all).
users of fe2 with wormhole bug, be warned, assasinations must be done in "normal" jump manner, if you shortcut over a wormhole route, the target ship is allways not there, also if you follow a ship using a shortcut via wormholes they will never arrive in the target system (i don't know exactly why, maybe data get's lost when you jump over the full range?).
a hint for beginners, don't arrive to early, they might get warned, time the arrival in the target system for a assasination as close as possible to timepoint when the prey leaves the starport.