The most common mistake that most people make when creating (or ordering) an ecommerce site is that they think that if they lunch the site they will have traffic but if you think about it the websites that are in the top 10 of google are the ones that are already established and getting a lots of traffic that way.
So what should you do? well the best way to get around this is to first create a lots of good and helpful content around whatever it is that you are selling and then publish that as a part of your site (That is why some of the big brands and name are creating blogs on their main site) in this way people that are simply researching about your product will find these blogs and if the content is helpful to them they may bookmark or even share it with their friends and come back to it. And in time your site will establish itself as an authority on that market and gains credibility with the client and with google.
So first start with the content and then move to the products. But that doesn’t mean that you shouldn’t have your products online already what it means is that have content first and then add the products slowly so your main focus will be the content and then you will move to the product.
This way you will have traffic and having some sales as a result while you are in fact promoting your site and your brand in the market.
For more tips have a look at Developers Creed.