I also completed the Stone Giant this week from the Bones II Expansion Set 1, as part of my ongoing effort to tackle some of the bigger figures from this Kickstarter. In thinking about what color to paint him, I decided I didn't want to do him just purely grey, but wanted to give him a little more pinkish flesh-like skin tone to help differentiate that he isn't a troll.
I prepped the figure in the usual way; soaking it in a dish of water with a couple drops of dish-soap added, then giving it a light scrub with a soft toothbrush, and then rinsing and drying. I then glued the figure to a 2" black-primed fender washer with Aleene's Tacky glue. The 2" washer was big enough to just hand hold, so I didn't glue it to a tongue depressor.
After the figure had the afternoon to dry, I gave it a coat of Ceramcoat "Matte Varnish" in the evening. The next morning I flocked the base, and later that afternoon I sprayed the figure with Testor's Dullcote.