Take great photos, invest in a camera that has Macro for those details, never put yourself or your own hands in any shots...keep them professional with as few distracting backgrounds as possible.
Start your bidding low. People are naturally competitive and love to bid.
Keep your customers happy by replying to any questions they have about your product.
Have great return policies and and shipping discounts, maybe even free shipping depending on the price of your product.
Lastly, be an honest seller. Don't lie about anything. If it's cracked and you think nobody will see it, tell them it's cracked, you can barely see it. When you get positive reviews, that will jack up your reputation with clients and that's what you want.