My experience has taught me that conventional Soldier fighting doesn't work. I've abandoned the class altogether above bronze. I've found a Salarian Engineer's Decoy to be very helpful, with the distracting and all that. works great for Geth, not as much with Reaper foes.
Also, a Vanguard's Charge works, following up with Nova attacks with full shields and very light-to-no-weapons for very fast recharge times.
Best of Luck. I don't play ME3 too much right now, but you can send a message my way on XBL for any friendly support! Gamertags linked to my Profile. If you're on PS3, then that sucks, cuz I can only do Xbox 360.