before you can earn money at a store, you have to have people visit the store. So you have to get traffic.
Best way to start is adding your blog to as many lists as you can find. Most of them require a link back, so put them on your blogroll. You'll start to see people roll in, but you have to keep them there with interesting content.
Once you have a fanbase, start affiliating with whatever company or store your audience would be interested in buying from.
One of my best affiliates runs a Q&A site on diamonds where he recommends specific diamonds to his visitors as he is a diamond expert. While he answers questions, he recommends diamonds, and they buy them, and he gets a cut. that's a GREAT way to make a lot of money. You need the SEO, the traffic, and the expertise to recommend whatever it is you want to sell.