Depending on a persons location and permitting issues you could always look into sea cans. Stack them, use the lower one as your workshop as it would be considered permanent with electrical installed. The top you may be able to get away with having without permitting or building codes being an issue and store parts as you complete them.
Every receptacle location I'd put a quadraplex set in as others have mentioned you can't have too many outlets. For good small workshop layouts I'd search small motorcycle workshops as a good starting reference point and adapt their layouts. I've found a few in the past that look like they use space efficiently when I was looking to make my 10'x16' shed into a workshop.