Disclaimer: I am not an active entrepreneur nor am I engaged in e-commerce. Just a reader, chiming in.
I'm assuming you have a good and working product so I won't talk about "making the best product that fits your clientele." I'd suggest finding forums on which the products you sell are discussed. Don't put up spam posts on the forums. Instead, involve yourself in the discussion of a particular and show that you have knowledge because you sell that item in your (online) store. In other words, don't cram your store into peoples' eyeballs. Show them what you know, how you know, and where to go if they're interested in more.
Blogging is also a good idea. Seems like blogs are almost required for startups these days.
I'm assuming you have a good and working product so I won't talk about "making the best product that fits your clientele." I'd suggest finding forums on which the products you sell are discussed. Don't put up spam posts on the forums. Instead, involve yourself in the discussion of a particular and show that you have knowledge because you sell that item in your (online) store. In other words, don't cram your store into peoples' eyeballs. Show them what you know, how you know, and where to go if they're interested in more.
Blogging is also a good idea. Seems like blogs are almost required for startups these days.
Goodluck.