We had two colours for our marble base, a creamy whitey one and a pinky colour. I took bothbuckets out with me onto the cloth and blended the two while they were wet.
Once we were done, Rachel suggested we do a spatter of both colours over our blend just to break it up a little, I think this really seemed to help but was sublte enough not to attract too much attention.
The next step was to add in the veining. Rather than using a feather, I used a large long rag and dragged it around making sure there was enough variety between big and smal shapes. I went in with a piece of string to add in a few finer wisps too.