Only offering a good product, isn't enough. A number of different banners is nothing. Ask yourself, what kind of sites do you like. You personally, would also prefer sites with a lot of information. Sites where you can learn and entertain yourself as well.
Visitors also like some free offers, services, or a small gift.
The better content you have, and the more you have to offer, the more visitors will bookmark your site and come back. As long as you are not an owner of Coca Cola, you should do so. And of course, how serious do you think you're customers are going to think you are, if you couldn't afford to spend a small amount of money to register your own domain name. It's like a company with only a PO Box for an address. Here you can check a domain name for availability, as well as register it.