I went to college for two years and studied Computer Science and decided that computers was more of a hobby for me and not something I wanted to do for the rest of my life. This past summer I started selling on eBay and am doing it full time now.
If I am shipping a computer or something big I will ship it with UPS, otherwise I usually ship with USPS.
Return policy
I really don't have a return policy, but if you buy something that doesn't end up working or you are not satisfied with the product I pretty much always give you a full refund.