You've got a nice jump in quality from the first to the second pictures - your colour choices are solid too.
Your base coat on the skulltaker looks good and is another improvement over the bloodletters. There's hundreds of great, fancy techniques out there but the base coat is the most important to getting a nice looking model.
Try base coating the bone parts with a dark brown, then use bone over the top and wash with a light brown wash.
Use the same technique with the gold too (replace bone with gold).
I'd also advise keeping the yellow for the eyes or going for a brighter green - the face should be the focal point of your miniature and the yellow draws attention far better.
Don't forget to do your bases too. Some drybrushing over sand & grit gives a huge boost to aesthetics.
Will look forward to more pics - keep it up