I'd echo sundevelpeg's advice to attend trade shows. Many shows are invaluable for both finding merchandise and advice for retailing those items. And best of all, everyone there is ready to sell you wholesale.
This may seem silly, but the book Retail Business Kit for Dummies is pretty useful.
Finally, when you figure out what you are going to sell, think about the "amazon effect." Is the same product sold online cheaper? If so, perhaps it'd be best to find a different brand to carry... Then on the other hand, you have to get your online store up and running. When I started selling online in my business, I was shocked how many folks buy online.
Good luck. I'll be sure to stop by next time I'm in the neighborhood.