is that a Daz doll your using?? do you scale it up for modeling? (posers tiny scale makes modeling harder). I think everyone does the details in diff ways and can only give general tips witout seeing the mesh you need help on, things like cuffs/hems are easier if you duplicate the last row of polys scale down slightly then bridge loop it back into the mesh(check normals), can do the same "trick" for seams (eg side leg of jeans) just add a loop cut or two, cut out the seam, move it away a little bit and bridge loop it back in. Some people use the sculpting tools for details but need to watch the poly count if it gets too high you may need to retoppo the mesh. The worst place I have found is the lapel on a jacket!! is many many dif directions for the mesh to be pulled/pushed I often end up moving verts on a one by one basis(dont forget symmetry or the mirror modifier they save you half the work)

ps nice modeling I hope the tips help a little