I have tried to match the reference with my model using liquify in photoshop, but it's impossible since I can't see my model underneath, just the ref. image and therefore I can't match it exactly.
Other method that I can think of (and that I have tried but gave up) was using the zproject brush to paint from different places of the ref. image. Seems too unaccurate and I think there must be a better way.
I'd greatly appreciate any advice on this. Thanks!!