Well at first you come up against a titan, just stay hidden (not next to the cover but back a bit so you don't get hurt) then come out and fire a few hailstorm bullets, then go back hidden. After that take out the hybrids with the bullseye/frags, then another titan, use the same tactic. Now keep going, when you hit the switch go to the left and stay there. Fareye some of the hybrids that are running to you and frag/bullseye the rest. Now fire at the reactor with the carbine/hailstorm (go nearer so you're bullets connect), when the angel comes deal with it with the LAARK (use the mini rockets to deal with it in one/two hits), now go round to the next reactor, take out anything that comes, and keep going. Try not to get surrounded. I don't have a concrete tactic after this point (my one usually involves using backlash grenades, which you get on a second playthrough)

Good luck!