Question about Isolation Moves

[mojobluesman]

Assume I am on the button or in the CO, one very loose player limps from middle position and I would like to isolate him if possible.

I've been running into a lot of situations where I have a small pair or pretty good high cards, but nothing special and the SB and BB have been playing rather loose. When I go for the isolation, one or both call and I find myself in a position that is not particularly attractive.

Are there some sort of guidlines for the isolation move as far as the blinds playing style goes?