If you have an online store, you'll inevitably be competing with a ton of other stores online, which could make it difficult to gain a following. To get people's attention, consider looking for an interesting hook or angle that could grab a select group's attention. You might find that you'll have better luck reaching a small but targeted audience than to try and sell to everyone. Science-fiction aficionados, sports fanatics, amateur chefs—the list of segmented, viable groups of consumers is endless.
A few years ago, before the 2008 election, I opened an e-commerce site of my own. Back then, before most people even knew who Barack Obama was, the best odds in the house were that Hillary Clinton would walk away with the Democratic party nomination and most likely be the next president. She was also a very polarizing political figure, and people who followed politics had very strong opinions about her. I launched a site called I Hate Hillary (at the now-defunct IHateHillary.com ) not so much because I actually hated her (I didn't), but because sometimes you need to rattle the cage to get some attention. Using freelance writers, the site featured regularly updated posts about Hillary, other presidential candidates, and the state of the race in general. It featured poll results and videos, and engaged people with debates, surveys, etc. There was also a small store where visitors could buy anti-Hillary mugs, bumper stickers, T-shirts, buttons, mouse pads—you name it. Without my even trying, the site quickly built a nice following. Soon, it was generating close to $500 a day in high-margin sales—and this was still just in the primaries. The hook worked. (Of course, what I didn't anticipate was that Hillary would lose the primaries, so the whole thing was pretty short lived. But it went well while it lasted!)