If so, what are you doing if you want a solid color for a collar for example? I thought I could just leave it blank and it would use the background color. But it adds a transmap and I think it masks it out in Poser if you do apply some sort of texture. I thought about saving some plain colored textures, but I'm not sure how big to make them etc.

thanks.

I use StitchWitch and use your second option.

If you haven't really created any transparent areas on your outfit, I imagine you could leave off the transmap and set the color in the poser material room. Or you could remove the transparency for the collar if it's a separate material in the material room.

If you use a solid colored texture map, be sure to save at 300 dpi. You can make them fairly small as StitchWitch tiles them, and since they're solid they'll be seamless.

I don't know what graphic application you're using, but you might look into brushes or filters to give even your solids some sort of weave or fabric like texture.

save your solid colour textures at 2048 x 2048 as a general guide, or at 1024 x 1024 if it is only to be used on small items.  if you want the collar to be different to the main item (unless the collar is a separate piece) you will need to use a separate new layer otherwise S/W will treat it as a transparent bit.
do the main layer up to where the collar is to start, and then on a NEW layer(spline) start the collar at the same points as the main layer ended. seemed to work for me without messing with transmaps (which i still don't know how to use properly)

Thanks for the tips.