This is a good step-by-step guide for setting up an auction, if you're not sure how.

It's best to research closed auctions to get an idea of what you might expect your item to sell for.  This will help you figure out what you should set your starting bid at. I normally like to start my auctions at a little above what I paid for the items plus a little extra to cover the fees associated with the auction.  This way I won't lose money.

Write a clear, concise titles and descriptions. This will help save you time by cutting down the number of questions you'll receive from potential bidders. If you do get questions, be sure to answer them promptly.  If you don't answer them quickly, the bidder will bid somewhere else.

Be sure to take clear pictures of what you're selling.  Auctions with pictures almost always sell for more than those without pictures. You'll eventually want to invest in a digital camera.  Here's a great deal on one:

HP Photosmart 435 3.1MP 5x Dig. Camera - Save $10!

When just getting started though, you can take pictures with a regular camera. You'll just have to take the film and have it developed, then either have the photos put on a CD, or scan them into your computer with a scanner.  You should also edit your pictures before uploading them to Ebay.  This makes them look so much better and load so much faster on Ebay. Focus on the main subject by cropping the picture.  You don't need any of the background stuff anyway, just the main subject.  Reducing the photo size will also make the picture load quickly.  Most people won't wait very long for an auction page to load, so you want to be sure your page loads quickly, otherwise you'll be missing out on bids. A good free photo editor is IrfanView.  Here's some good tutorials on using other popular photo editing programs.  Here's some tips for taking pictures on a budget.  More photography tips.

Making your auctions look nice can help improve sales a lot.  You can easily create nice looking auction templates, just go to:  Auction Insights | Auction Riches | Auction Spice | Cool Ebay Tools | Auction Lot Watch | Xample.net | DeSaCS.com

Try to have your auction end in the evening on a weekend, since there's usually more bidders on Ebay during that time. I find that Sunday evenings usually work best for me.

It's usually best to state in the auction what the shipping costs will be.  You can set a fixed shipping rate if you want, or charge actual shipping. Ebay now has a built-in shipping calculator that is very helpful.  Just enter the weight and your zip code when setting up the auction.  Bidders will be able to enter their zip code, and see the shipping costs. 

You should decide what types of payments you will accept, and be sure to include that information in your auction. I take Paypal, PayingFast and Postal Money Orders only. I really like electronic payment services best, because they allow you to instantly receive the payment [no waiting for the mail]. I don't take any checks, since I don't know the people.  Also because my bank charges high bounced check fees.  I'm just not willing to take the risk. As for money orders, I only take the ones that are purchased from the post office, because banks treat all the others the same as checks and people can put stop payments on them.  Postal Money Orders can be cashed at the post office, so you can get your cash without even going through the bank.  Here's a list of payment services you might want to check into:  Paypal | PayingFast | BidPay | CCNow | MyCheckFree

You should ship items out as promptly as you can once your receive the payment. Some people like to ship items out immediately after receiving the payment. I don't like running to the post office every day, because I have 3 kids to drag along.  I only go about once a week.  I state it in my auctions, so that bidders will know ahead of time that the item may not ship out right away.

You can get free USPS Priority Mail boxes and tape here: Free Priority Mail Supplies.  You can print a free shipping label with Priority Mail and Free delivery confirmation here.

Still need more information?  Here's some helpful E-Books that can help you improve your Ebay auctions. A lot of this information is absolutely free!