One problem I have with fighting games is that sometimes my hands just do not want to do what my brain tells them to. I've got a pretty beastly combo set up in Marvel vs Capcom 3 with Dante, Iron Man and Super Skrull but more often than not I can't manage to make it work. My thumb mashes the attack buttons when I'm trying to be precise, I fumble the quarter circles, I keep back-dashing instead of just blocking, the list goes on. All griping aside, though, it is a fun game, I'm enjoying it a lot and I do seem to be getting better at it. Oh, and in the proper hands Phoenix is totally broken. Just so you know.
Edit: See, this is what I try to do. It doesn't go as well for me.