Avbat
A few good acrylics are fine. Flesh, or make your own from Raw Sienna, Burnt Sienna & Ti White. Black, & a few other col. you need for say different hair col. or eye col.
You can get sets of chalk pastels for under 20.00 US. I usually use several shades of brown (also, don't be afraid to mix the powders as you would with paints to get the col you want) Use some gray for stubble, (black is to dark & sometimes darkens following a clear coat) Pinks & some brownish reddish tones for cheeks,ears, nose chin, adam's apple. A blue for veins & purple/lavender on upper lids (sometimes)
The trick with pastels is to make the piece NOT look like it's painted. There is a tendency to over do it. Don't. That's why I suggest blocking in the hair. It gives you an idea with something for contrast as to when enough is enough. Better to under paint than over paint.
Brushes should be your main concern. Don't go to inexpensive. That is unless you are using an airbrush for the base tones (which I strongly recommend) Testors/Aztek make one that is beautiful to work with.
As far as brushes for the pastels, you don't need pricey ones. Just descent quality. You are working with powder not paint, so brush lines are not an issue. Think womans make up (ok, & some guys, I got friends that do it & you can learn a lot)
One of the best things for reference is your own face. Look in a mirror not at the face, but break it down into a collection of colors. You'll see what I mean.