There are a lot of good points here to keep you occupied and focused on improving for quite some time.
Since you feel confident in your serve but face inconsistency in your return, here's a suggestion that may or may not help you.
I find that many times returning begets errors from indecision. Before the serve, you may want to tell yourself, "If I get a forehand, I'm going to hit it here and if I get a backhand I'm going to hit hit here".
If you're not quite to the point where you want to start thinking that far ahead, the other option to build return consistency would be to aim for a single spot on the other side of the court and only hit returns there (I'd suggest hitting at the T or middle of the court and focus on good net clearance).
The idea of both is to eliminate the hesitation and doubt of what to do with the serve return. The more balls you get in play, the more often you have an opportunity to break serve.
Boris Becker Melbourne
"To resist despair in this world is what it is to be free"