Make sure to be strategic in how you use your weapons and biotics during combat; experiment with your talents and see what combinations will work best together with your pistols and shotguns. For example, you may want to begin a fight by casting Warp on enemies, where it lowers their defense as well delivering some damage every second. As they're taking damage, you can then fire your pistol to finish them off, so the fight should end more quickly.
Another strategy is to attack first with Lift and Throw and then use your shotgun. When an enemy is falling down from Lift, he will be on the floor for a few seconds before he gets up. Take the opportunity to run up close to him and blast him away with your shotgun. This way, you won't have to worry about an enemy firing as you run ahead.
It's poor game planning when you're just gunning around without relying on your biotics to give your weapons an advantage over your opponents; going in this route will not always be a good start during a fight.