At the moment, I am trying to make some asteroids that will be featured in a (top-view) space shooter game ; These asteroids will be rendered and the resulting images will be used to texture flat mesh objects ; So no texture baking or UV unwrapping is necessary here.
After having read quite a few documents about asteroids in general, I must admit that it is a very fascinating subject ; I suppose one could spend a life time studying them !
Bear in mind that the colours in the asteroid photo you have posted are enhanced and/or false - designed to highlight detail and/or different mineral compositions.
Too add some variation in brightness however - you could throw the new pointiness attribute into the mix.
Thanks for the help everyone.
The big craters are now less deep than before and I added a pointiness node to the asteroid Material.
Today I will try changing the lighting and the vertex colors, as to see if any improvements can be made.