Over the last couple of years, I have learned the hard way how NOT to get taken advantage of when buying on eBay. I thought I'd pass a few "How NOT-TOs" on to you.

1. Read the Feedback! EVERY TIME if it is someone you haven't purchased from before...and even if it is! Why? Remember that a Seller with thousands of Feedbacks can have A LOT of Negatives without affecting their Percentage rating! You MUST check those Negatives out...don't be taken. You can even attempt to contact those unsatisfied buyers. Ask them what went wrong.
2. If the seller deals in DVD's, VHS, CDs, etc. Carefully check their return policy. My first time being ripped off was by a Power Seller who accepted returns for exchange.....but only if the item was unopened. My DVD wouldn't play....the seller wouldn't acknowledge my repeated e-mails.....for 89 days. So make sure they accept returns. You don't know if it's a bad or broken DVD or CD until you open it or play it. What happened? On day 90 I left him a Negative.  On day 91 HE left me one. Something to think about:  A lot of people automatically leave the Positive BEFORE watching, listening to their new purchase. Result: Seller gets a FALSE Positive....Buyer has left a Positive...but has something that is NO GOOD. Also BEWARE of Bootleggers. If  your DVD or CD has an off-color cover, or isn't "quite right" send it back.
3. Don't be dazzled by the "Power Seller" Icon. It doesn't always mean that the seller has been on eBay for a long time. It just means they've done a lot of business (over $1,000) in at least 3 consecutive months. Check to see how many transactions they've handled. How long they've been around. Sometimes this can help....but not always.
4. Item Decriptions & Picutres: Avoid purchasing from a seller who gives a very short description.....just a few words. If you feel you really want to bid.....make sure to ask the seller questions; and ask EARLY. Don't wait until the last few hours to ask. Then....Take their answer into consideration. Keep their response in your system. Picutres: they are expensive for sellers....unless they subscribe to eBay's Picture Manager. The result is many sellers do not put more than one or two in their auctions. If the picture does not show the whole item....all sides....or only shows a small portion of the item..(as is often the case with jewelry) do not bid......or ask for more pictures. Some sellers just omit important info in the words, but will show you a good picture. Remember...the picture is part of the description. Example: If a beanie baby is missing it's name-tag...and the seller doesn't say that in his ad...but the picture shows the beanie with NO tag and you don't notice it.....he can honestly say it was in the description. This kind of thing happens every day. You must pay close attention.
5. Avoid bidding on an item that is in the final minutes if you haven't already thoroughly checked it over and asked all your questions...studied the pictures, checked the Feedback etc. Close your eyes and let it go. You are much more likely to get taken advantage of in the final minutes!!! Some sellers count on it!
6. Shipping: ALWAYS find out the shipping cost ahead of time. If you ask and the seller does not give an adequate answer, DON' T bid! YOU are responsible for the shipping cost and will have no recourse. Even if the seller states that the price charged will be "Actual Shipping".  Actual shipping? By what Method? You should always know what the cost will be. A reputable seller will give you at the very least a low and high estimate. Most can tell you exactly what it will be; especially if it is within the USA. About handling: most sellers do charge a handling fee; this should be expected. Packing materials, boxes, trips to the post office, and time all cost a seller money. This doesn't mean however, that they have the right to charge an exorbitant fee for handling. Always check the terms in the auction. Sellers often will state what their handling fee is. Some provide the shipping calculator or just give you the flat rate.  If they don't, ASK. Go into this with your eyes open and don't get caught by surprise.
7. Retaliatory Feedback: Personally, I don't believe in it. If I see negatives on a Seller's feedback...I check to see what feedback THEY left for the buyer. If they waited and left nasty feedback afterwards...I won't buy from them. Of course if it was a Non-Payment issue that's a little different. But if a buyer paid within the terms set by the seller and the seller still leaves a negative in return...that is retaliatory. And a seller who does that is probably not the kind of person you want to do business with. A little extra note: If you are unhappy with your item, ALWAYS attempt to contact the seller before leaving a negative. ALWAYS. Most times, these matters can be settled. Most Sellers are reputable and want you to be happy.
8. Your idea of perfect might be different than the seller's idea of perfect. Always ask for details. Especially when purchasing glass, books, etc. With these type items it's always good to ask extra questions, because sellers can miss small flaws, we/they are human.

Well, that's all I can think of right now. Some of this stuff might seem pretty basic to some of you....but hopefully this will help a few new buyers out there, and a few "old-timers" too.

PS: All three of my "rip-offs" were by Power Sellers....two with very high feedback counts...one with less than 300....

Of the three, the first two could have been avoided if I had only followed my own hard-earned advice above.  The third....well, that was just bad luck and one of those things.

However, I have found that the overwhelming majority of sellers (including Power Sellers) are honest people. Just be aware that there are a few bad apples out there. Be thorough...it's your hard-earned money you are sending to these people.