Hello this is the "original hammer" to solve your delema I would have to recomend the free tutorial with the "franky" character this tutorial covers the method you are requesting.
The problem I think you are enduring is that you have to make sure you have no loose ends on your polygons that is they all have to be 4 sided for example and no lines or faces in between but as I had said watch the video anyway it has given me a great introduction to maya.
And thanks to the creator that was a very good tutorial.
ERIC B.