In addition to what frugaliknowit mentioned, realize eBay is very safe if you follow their guidelines. Don't trade behind the scenes, like after an auction ends. Use paypal. If you're contacted by the seller or others about the same or similar product and are offered the item outside of trading through eBay, don't do it... if it's a scam you won't have any recourse.
I'll add that for items you bid on, as opposed to items you buy at a "buy it now" price, decide what it's worth to you and bid that, meaning bid your absolute max. If you're outbid, don't raise your bid limit. Another one will come along soon. If you want to raise your bid, ask yourself are you raising it because of the competition aspect of being outbid, or because your original bid wasn't your true limit? The proxy bidding system should work for you if you let it, set your limit and forget about it.
