Having a good shotgun helps. I'm using the Geth Plasma Shotgun, it has great range so you can even take people out at a distance. As for the charging into bosses, it depends on which ones. I've found Ravagers, for instance, to be pretty easy to just charge shoot, then charge in and heavy melee it to death.
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You beat yourself up with your past. Don't blame yourself, blame the world. Blame God. Blame me.