I found the best way to do this was to play the game, earn some money, explore and find stuff.
Or you could do it the easy way and use the spoilers forum to locate all yer stuff. The game does get a tad broing once you have a Titan and 6 level 10 guns and level 10 shields...
Still hunting down a lev 10 turret... and no I dont want to know where it is...