About a year ago I had a small group of beginner weavers who wanted to move on with their rigid heddle weaving. One of them was Jane Cowan, who has recently sent me a picture of her lovely rug, woven for her daughter on her rigid heddle loom.
Jane wanted to know it there was a book that could help her design different "patterns" on her rigid heddle. After seeing this beautiful piece of weaving I suggested "Colour and Weave Design - A practical reference book" by Ann Sutton. It's out of print now, but there are one or two second hand copies available and worth having in your library if you can get hold of one.