Dear Willow,
If asked to define a pastel palette, I think most pastellists would smile for a couple of reasons. First, the question, "What's on your palette?" is the same question as "How big is your bank account?"
Since pastel can't be mixed in the same way as liquid paint, color results happen one of three ways: direct application of the desired color; layering of colors, or the use of broken color to create optical mixing.(Therefore, you needs LOTS of sticks.) So the number of sticks you actualy own might best be thought of as an inventory, from which you pull a subset, a working palette for a given painting. For me, it makes more sense to think of
resulting colors, that work well within a given harmony...and one of the reasons I like to think through color harmony before I ever start a painting.
For someone new to pastel, I usually recommend starting with a standard (portrait or landscape)set of approximately 48 colors, supplemented with darks, either hand-picked or purchased as a set. Most major manufactureres now offer darks, as a set of 12-18 sticks or so.
It's important to have a full range of values, as well as a full range of hues, and both warm and cool temperature versions of each hue. If you have the chance to hand pick your darks, you can take the opportunity to sample several different manufacturers,and get a feel for the characteristics of each, as they are VERY different. Then you can add to your inventory with different sticks depending upon what you like, and how you will use them. If you are still feeling a little flush, go for the big set of NuPastels.
Some number of years ago I took Doug Dawson's workshop, and he has a wonderful approach to a limited pastel palette: pick 3 sticks, one dark, one medium and one light in value, each in a different hue. The only caveat is that the three of them should look beautiful together. Then take the painting as far as possible before adding a fourth stick, and so forth. For those of you who know Doug's work, it is hard to find richer, more beautiful harmonious color anywhere. (Also see his excellent book,
"Capturing Light & Color with Pastel", by North Light Books)
The other thing that makes us pastel painters laugh, by the way, is that even if you have a thousand sticks, you can be sure you will never have EXACTLY the right color.
Kindest regards,
Chris