Substance Painter - Import Model and Paint

 1. Save the Maya File in FBX or OBJ and import into Substance Painter

2. the Material List will on the top menu 

1)It's very important to create a Material file for each of the parts, therefore you can click each of the Materials and Paint it. 

2) Layout the UV map for each part of the Material before you bring the file into the Substance Paint. Otherwise, the files will overlay and hard to paint.

3. Then you can add layers and paint on the body.