You think you have a problem.
I can nail inside rollers but have difficulties smoothing out the outsiders!
What I've been doing for practice is rolling horizontal figure 8's. Aileron input remaining constant and concentrating on the elevator/rudder cross overs. It's kinda grovy once you relax into the mode. A valium helps... honest!
If your without prescription, take your old aeroplane, plenty of hight and just start doing 'em. relax... relax.. relax and let it flow.
May the force be with you.