That's why market research is so important.
You want to understand what are the bestselling items.
(You do that through
http://pulse.ebay.com )
then you want to study successfull sellers.
How do they write their titles?
What about their descriptions?
What pictures do they use?
For what prices do they sell the item?
When do they end the auctions?
In what categories do they sell it?
Do they use any special featurs (like frame, highlight, bold, etc.)
Study that for a couple of days, then you will have a much better feeling for what sells and what not, and how to sell it.
The next thing of course is finding products.
Some people recommend salehoo, but in my opinion
http://www.worldwidebrands.com is the best on the market. You should sign up for their free newsletter, there you get one free dropshipper every week. This way you want have to invest in inventory and can get your feet wet a bit.
Hope this helps.
Johnny Bay