GW martian iron earth and martian iron crust. To make it a bit more varied in the textures I try to put one of them first over 50% of the base give or take in a varied pattern then while it is still wet out the other one on the rest and wet blend the areas where they touch a little bit. Once they are dry you will have (in my opinion) a more realistic finish between cracks and dirt textures. Once dry just a light dry brush with any light brown or sandy yellow color to add some definition and it makes for a good table top level base.