1. I’m still figuring out sleeves.
2. more than one layer in for backgrounds, eh?
3. I can’t seem to figure out how to make hands hold onto things convincingly.
4. File naming scheme
5. The werewolf form’s fur is weird because the item I used for it was some kind of hide wrapping.
For #4, be specific. The efforts you’ve shown so far tell me we’d like you around long enough to run out of generic names. Use the character’s name when possible. KS, then KSInWereForm, etc.
#2, YES. If you want to save time, check out the custom backgrounds and borrow till you’ve had practice with them.
All of your odd numbers could involve masking practice and experimentation. Keene’s sleeves have a good start; just mask something onto a transparent forearm (alpha to 0% on each color) and build a cuff out of something like neckwear. Hands holding something are usually best done in multiple masked pieces. –As for the fur, you might even mask parts of a furry companion onto a few appropriate shapes. Pretty soon people will be saying ‘who was that masking man?’ 
