Paint with Paint.
Really good art tips remain good even if they are intended for a medium other than pastel.
David Cheifetz is a still life oil painter, but you will find quite a few nuggets in Lago's summary of his workshop.
David says, "You want your lights to be painted in mostly opaque colors because they attract the most light rays visually." Have you tried this in pastel?
PSST Blog is written by Carolyn Hancock