There is not universal answer to this question. It all depends on the industry, experience in the market (which forms of promotion has been already used) and the budget. The most popular forms, from which without doubt you should start are Adwords, SEO and adding your offer to the price comparison systems (if it fits your industry and products for this type of tools – for example things like arts and crafts are not suitable for this form of promotion and sales of equipment such as mass electronics like to be the best match). The following steps should be to target the sites and industry catalogues. Then, web forums about topics related to the shop. And then we just continue with conventional forms of advertising – such as advertising in newspapers, flyers, billboards and more. Generally, online shop should be treated like any other business. Ways to reach customers are similar.