Personally I wouldn't have picked a subject that is almost all hard-surface for your first crack at it, but it'll be a useful learning process for sure. I second rdmlegend's advice to do hard surface bits subtractively- much easier to keep 'em clean that way.
This will be a cool project, Sculpting is a lot of fun. From my experiences I recommend additive for organic shapes and subtractive processes for machine made objects such as his armor. Don't be afraid to really mass him up with clay then get in a break it away with your tools. Can't wait to see more. =D