A quick guide to making your miniatures look sandy, using only acrylic paint. This method works nicely if you don't have any pigment powder or just want to maintain an extra bit of control.

1. Thin Steel Legion Drab down with lots of water, aiming for a wash consistency. Slap this thin paint all over the general area you want to appear dirty. Allow some to build up in recesses and try not to be too neat.
2. Accentuate where the dirt will have build up with some Tallarn Sand , thinned in the same way. With this layer we are trying to give the effect of multiple layers on the feet. So try to mix it up, with splashes on prominent points, as well as putting extra into areas where the previous layer has gathered.
3. Finally take some Karak Stone . Don't worry about this layer being quite as thin, this is to be used only in deepest part of recesses.