I have been buying on ebay for 7 years.  My wife calls me the ebay King.  We have bought about everything imaginable including 3 cars, pick-up truck, kitchen flooring, dishwasher (2), refrigerator, range, watches, jewelry, digital cameras, postcards, shoes, clothing, DVD, video games, tools, industrial tools and instruments and more.  I have probably completed over 600 transactions on ebay.  Have only once been stiffed where the seller did not send   the item.  Have had a couple times where I had to threaten and file complaints over items not received or been refunded.  Have had two one persons file a retalitory negative comment.  One was later kicked off ebay, but they would not remove his caustic feedback.  Here are my recommendations;

1) Pay attention to sellers feedback.  If there are several about slow shipping or cheap items, don't even try

2) Search by combining other key words that might reveal bargain such as "barely", "wife" ("wife used it a few times" or "is telling me to sell" works good) "gift" (someone received it as gift and is selling) "must" (must sell) and "reserve" for low or no reserve, "birthday" (selling an uneeded birthday gift).  You can probably think of others

3) Use Advanced Search for Completed items using specific words to see what prices past similar items have sold for

4) Pay with PayPal and credit card (in case you need to dispute payment)

5) Only bid on items with known shipping cost (Have been burned a few times with outrageous shipping cost after winning item)

6) Try and bid from people who have feedback of selling variety of items (ebayer's who like experience of selling)

7) Ask questions, if people are sincere and honest, they don't mind answering questions and also reveals some of their honesty or personality

8) If shipping is late, I don't get nasty right away, but start with question to them like "when can we expect item", "Have you shipped yet" (threats don't seem to help, and you really don't know who you are dealing with)

9) Only buy items with photos

10) Don't bid early, let others set the value early or increase interest, best to hold off till near end and try and beat out last second bidders

11) If it is a "must have" go ahead and bid your highest price early and hope it ends up being high bid

12) For commodity or high quantity items, switch to Buy it Now, and then sort the list on price - can quickly find the lowest price item you can buy immediatley

13) Search outside category for key words, sometimes people don't get item in correct category. 

Thats about it.  We have enjoyed using ebay, and found some amazing bargains.