Check out a nice guide by ‎Daniel Evan Ries to dealing with complex models.

Check out a nice guide to retopologizing and baking complicated shapes from ‎Daniel Evan Ries. The artist was working on a low poly bandana and he had a hard time dealing with tons of wrinkles, so came up with a cool method. Daniel used Maya and xNormal in this case.

The guide was originally published here.