You say you want to get better but I'm pretty sure you're only talking about improving your DM ability. There's a lot more to getting better than just DM (of course, DM plays a big part) that I'm sure you'd want to work on if you truly wanted to get better (good communication, coordination with teammates as a result and so on).
Pugs/finding a team to scrim with and commit to would be a great way to work on those "other" things.