I've never used etsy before, not even as a buyer! I'm still learning how the site works, what it looks like, and narrowing down choices of which kind of art to sell. I am a jack of all arts ranging from painting (watercolor/ink/oils) to chainmaille to felt.... trying to figure out if its better to have lots of smalls, or spend my time on larger projects to sell at higher prices.
In other words, my shop is nowhere close to ready for business! Since my product isn't ready yet, I'm researching for the best advice I can find on all topics new shop related.
Specifically, what is the one thing you wish someone had warned you about before committing to opening a shop? Also, what item (or type of item) in your shop is the best seller?