When should I isolate???

[Rock Solid]

Recently I have been re-evaluating my play, and I think that one of my weaknesses is that I don't try to isolate a weak opponent very often. Specifically, a player I know I can outplay, even if it means folding because I know he hit.
So my question is how often should I be doing this? Is it as often as possible? Should I loosen up my raising requirements in order to get it heads up with a weak tight? Any advice is greatly appreciated

[SpaceAce]

If you're sure you can outplay him, you want to play every single hand heads-up with him.

SpaceAce