Wow so many posts and so little advice.
1. Start an auction on a Saturday or Sunday and use 7 days or a Monday or Tuesday and use 5 days. Start at around 5pm Central or Mountain time to get the best time for the whole US. Know that only the first 12 hours or so and the last 30 minutes are when you are going to get bids. The remaining time is for people to watch your auction and hopefully remember to bid at the end.
2. The reason so many prices end at $X.99 is that Ebay charges per $10. So an auction that ends at $9.99 you have to pay Ebay $.65 while an auction that ends at $10.00 you have to pay $.90 (or something like that, point is that it's more). Also start your auction with a $X.99.
3. Selling things for less than $50 to make money is hard. Unless you get a good deal sell it on a forum. I think it's up to $50 but maybe $40 Ebay takes 11%. That's not counting Paypal fees, only starting and final value fees. That's the bare minimum. Something starting and selling for $10 will be around 18%.
4. Starting an auction low on a common but in high demand item is a good way to save money (Gauntlet for the GC comes to mind). If the item is rare and in low demand you are better off starting at a high price because someone will bid on it (within reason) and you might only get that one bid.
5. Include free shipping. If people see that in your title they are much more likely to click it and check it out. They know you aren't trying to scam them on shipping. Just figure it into your desired ending price.
6. Buy It Now is great. People don't like to be hassled with waiting and maybe being outbid. It's only 5 cents and usually works for me. Just estimate a price that is reasonable but higher than normal. Figure in shipping. Make sure to have it be something like $29.99 rather than $30.
Hope this helps. People on Ebay are suckers so don't be afraid to ask for more than you would on a forum and the most random shit sells. Take pretty pictures and be honest.
Edit:
7. Use HTML and your own web hosting to post pics. That way you can post as many as you want and not pay for them. Use the stock photos as well.
8. Don't ship internationally unless they are willing to pay rediculous shipping fees. This isn't to rip them off but to protect you. I once paid $40 to ship a Sega Saturn to Canada as compactly as I could and I only got $60 for it (which seemed reasonable at the time). Because of that I had to charge a guy $40 shipping for a guitar pedal to Israel that wound up being almost as much as the pedal itself. I make sure international bidders contact me first to give them shipping cost estimates. And good luck to you if you accept bids from Thailand and Hong Kong because a lot of those Paypal accounts are stolen.
9. Ship out by the next day after you receive payment (2 at the most). People are very appreciative if you do that. Also it saves me from having to respond to every person and tell them 5 days after the auction that I finally got their item shipped out.
10. Only sell things you know about. I've tried clothes and computer parts before and my descriptions were weak and I wasn't able to answer emails as well.
Basically I think there's a lot of bad advice in this thread and it would be understandable for you to be hesitant to believe me as well as the others so here's my impeccable Ebay feedback.
http://cgi2.ebay.com/aw-cgi/eBayISAPI.dll?ViewFeedback&userid=drhezz&ssPageName=STRK:ME:UFS