Mayo, I've bought and sold lots of things on eBay (in fact, have a large pile of equipment I need to list, if I could only find the time) and would agree with most of what has been said.
Listings - a picture ( a GOOD picture) is an absolute must. Some buyers won't even bother looking at auctions without them, depending on the item. A complete description is an absolute must as well - look at the completed auctions for the items similar to yours and try to figure out what drives the prices higher on some rather than others. Often it comes down to the description - generally, the more detail, the better. BUT - lay it out so it's easy to read (bullets, headings etc. - use a bit of HTML) There is free auction listing software available through eBay for the PC, but not for Macs. I'll probably do my next round of listings that way, since I'd rather not spend my profits on either Auction Creator (only $10, but I can handle the HTML myself) or the more sophisticated eLister, which is now only available via a subscription. ($9.95 for 30 days, $29.95 for 6 months and $49.95 for a year)
I have eLister's predecessor, "PreLister" - but it only runs in OS 9, and its categories are no doubt long out of date, since Black Magik stopped supporting it a while ago (much to my annoyance).
I usually run my auctions for 7 days and start and end them on weekends on Saturday or Sunday in the evening, figuring that this is the time people are most likely to be home (not that lots don't bid from work!!!). I'm not sure if this makes a huge difference or not - but living on the east coast, I 'm not about to have auctions that end at 6AM west coast time!
I always send email immediately to my bidders at the end of an auction, and with only one exception have gotten paid and successfully completed the transaction. I use Paypal and money orders and discourage personal checks, though some will send them to you anyway.
I generally use Priority Mail - you can weigh your items and figure out the postage in advance from the USPS web site and include it in your auction listing. I know that when I'm bidding, I like to know what the shipping will be - because some sellers tack on handling fees etc. which can make something significantly more expensive than the actual selling price. Again, the principal of more information rather than less applies here too. Since the buyer pays the shipping (unless for some reason you decide to), it's up to you to choose the shipper and generally, you should do it to make the transaction as attractive as possible. Unless you can offer FedEx cheaper than Priority Mail, you'll find the higher cost of shipping makes your auctions less atractive to bidders. Priority Mail offers various options - including delivery confirmation. I just discovered that they have some interesting new services - label printing and online payment. Check this out:
https://sss-web.usps.com/ds/jsps/index.jspComes with delivery confirmation for free if you use the label printing service online.
Just a few things that came to mind...