nice drawing dude looks alot like red xiii in final fantasy 7

the wrinkle thing apears when lots of egdes end up on the same vertex. this is not always obvious bcuz when a face contains more than 3 edges, invisible edges are created for internal reasons..

one way to get rid of the wrinkles are to convert to polys useng the 'uniform' option and set divisions to 1 and level to 0.. and then converting back
this will make your base mesh heavier thogh :/

if you dont want that convert it to polys useing the 'vertecies' option and set level to 0
then split the polygons on the wrinkeld area.. to be sure to not get any wrinkle try to make sure the whole base mesh is made up out of quads (ie polygons with four edges no more no less) or at least as much as possible

hope that helps