First off, I'm not an Ebay pro. I've been selling for about 3 months now. I have learned a number of things though and have encountered a few unfortunate experiences already. I'm not a merchant, I just sell what I have around the house and have recently started to sell a few things for friends and family.
I am constantly checking out other Ebay auctions. I try to take pointers from the auctions that catch my eye---their layouts, the way their photos look, language and terms used, font size, etc. If the seller has a really high positive feedback score, I may print their auction page out for reference at a later time.
As for pricing, I usually do a search of a similar item and then follow those auctions to see what final price the items sold for. Some experienced Ebayers have advised me to start with a low price. I have done that with some success depending on the item---I find that it works well with electronics, jewelry and really nice clothing like leather or cashmere pieces. On some other items, this has backfired for me as sometimes the first bid turns out to be the only bid and I'm stuck with that selling price. And, with Ebay fees the way they are, sometimes I lose money on the transaction. Never a huge amount, but those 35 and 40 cent losses can add up.
I recently added terms to my auctions--I saw a number of Ebayers using them and thought it made sense. It outlines my terms for paying, shipping, buyer requirements, and leaving feedback. I took some bits and pieces from different Ebayers and then added my own 2 cents too. Now that I have those things outlined and included in my auctions, I feel a little more secure.
Of course, there's always going to be scammers. I was cheated by 2 parties who had paid for their items through Paypal and then withdrew payment AFTER I shipped the items. This was early in my selling days and they both requested USPS Parcel Post with no delivery confirmation---so there's no way to track the packages. I now only offer USPS Priority or Express Mail and I print my postage at home through my Paypal account or through the USPS website. That way, there's a "paper trail" in their records of my shipping these items. If there's a problem, I should be protected more so than before. As a result of my inexperience before, Paypal could not and did not credit me any of the money and there was nothing else they could do without my being able to prove that I did ship those items. My receipt from the post office wasn't enough as there was no tracking #. I will only ship to Paypal users who are confirmed and verified by Paypal now--meaning they have a bank account or credit card on file with Paypal. It's not foolproof, but I then qualify for seller's protection from Paypal.
There's more, but I'll stop there for now as I see this is getting long. Here's a link to my auction page. They're not the fanciest auctions--I try to keep my Ebay fees modest and they add up quick. Hope this was helpful.