Traffic – it's really what makes or breaks a website or blog. If you have good targeted traffic to your website or blog, you're on the road to success. If you have no traffic or very little traffic, then regardless of how great your products/services, you cannot do well online.
Think of your website like it's a brick and mortar store. If you build your store in a busy mall or in a strip mall, you have traffic. That traffic comes into your store and you have the opportunity to sell them. However, if you decide to build your store on the outskirts of town just off a highway suddenly you no longer have access to traffic and you are much more likely to fail.
Bringing targeted traffic to your site is key to closing the deal and selling them something. If you sell B widgets and your visitors are looking for D widgets, you'll not sell them. So make sure that when you are promoting your site you are doing your part to ensure the traffic you generate is targeted. Once they arrive on your site the rest is up to you closing a sale.