Use Assault Rifles and Pistols, you literally need nothing else.
Especially not Sniper Rifles, they're the absolute worst weapon type in the game. If you like sniping stuff, wait until MEs 2 and 3 for that.
Since you say you're going Soldier, allot talent points in such a way so that you unlock Immunity ASAP. Once you have that(supplemented with Adrenaline Burst, which is unlocked earlier) the whole game turns into a cakewalk, you can literally run around the game shooting stuff while laughing non-stop with no concern for your health, as anything short of a Thresher Maw or bumrushing Krogan will just bounce harmlessly off you, even on the hardest difficulties.