Carolyn,
A good place for you to get the wonderful Unisons pastels online is at
www.cornelissen.com. They have Schminkes and Senneliers as well. I think they probably have the Great Americans in Paris. (Sounds like a song).
Oh horreur, quel faux pas! From your conversation with Steven I realized you must be Spanish. Oh well!
If you can afford it try to get as many full pastel sets as you can. I literally have thousands of colors. When you have a large range to pick from your work will absolutley fly!
Try to work from life as that will really give range and expression to your color. I go back and forth, but rely mainly on models . I have a lot of beautiful photos but they seem so flat after working almost exclusively for over two years from life.