Where to buy desert send and how to paint skin colour?

Most full service pet shops that have fish, will probably carry aquarium sand.

It comes in quite a few colors and varies from course to fine.

And it's cheap !

( look up pet smart online .)

Thank you all 

stikpusher

For the flesh tones, I'd suggest that you look in the Vallejo color lines. They have multiple flesh tones to choose from. Pick the ones that you feel would work for that group.

BK

AK makes a skin tone set that you can mix colors for different tones and shadings,most manufactures,Vallejo was mentioned,Mig Ammo make sets,try to grab  one of them,will last forever and are very useful for figures.

Reaper brand acrylic paints makes a triad set of bronzed skin; base, highlight, and shadow.   Reaper is popular among fantasy figure painters.   Ignore the ghoulish paint color names on the bottle.  It's whats inside that matters.  They also make some fine dirt colors

Tan tile grout makes a fine start for a sand base.

For the flesh tones, I'd suggest that you look in the Vallejo color lines. They have multiple flesh tones to choose from. Pick the ones that you feel would work for that group.

As far as sand colors go, sand can range from gray, to white, to yellow, to pink or red, to black, depending upon locale. Figure out the area you want to represent, and work from there.