Sometimes the best resets don't take that much work. Find spots to stop hitting buttons where you could ambiguously cross up, cross under or do a low/throw. Like with Bella, c.LK, c.MK is a good spot to stop, because from there you can run stop to fake cross under or actually cross under, or wait to low/throw, or command grab. Simple, ambiguous as hell.
Also, if it helps you feel better, I can use the whole cast and I frequently pick random select. Yes, I'm incredibly masochistic. I do pick the assists, though. Can't pass up certain combinations like Double with Pinion Dash or Squigly with Excellebella, because they set up resets.
I started playing with every character because I wanted to have a better understanding of what each character could do and their strengths and weaknesses. I found that I had more fun when I challenged myself. I still got salty as hell when you won, because I never go easy on anyone, no matter who I'm playing as. So give yourself some credit too since I was going all out as best as I could.
Some tips, I guess. The neutral is the most important part. I know a few combos with everyone, a few resets and that's it. It's how you move and try to get the first hit that matters most.
If you're blocking, it's important to pushblock, absolute guard and pushblock guard cancel to stay alive and turn the tide.