Just a tip for those starting out in the world of creating websites and trying to rank:
Search engines appreciate themed and focused content. Throw in a good domain name and get some backlinks from similar websites, and you are ready to start ranking in search engine result pages, or SERPs for short

When you get some good traction, you may want to add more content such as forums etc. However, starting small with a good product selling page coupled with some nicely themed articles can get you going. (Note, I am not talking about sales pages. Other people here are better to advice about those.) Should you get enough incoming link juice, you can start pouring it into user generated content.
Niche websites are also advantageous since they are relatively easy to research and create quality content for. Find popular keywords using a
keyword research tool, and then start creating unique articles, preferably with some new angles to improve chances of getting linked. Doing this, your content and theme of website will match what you are trying to get your product and selling pages to rank for.
If you become really successful in getting inbound links, you can even start looking into if you can sell or bundle quality affiliate products with your own offering. Either create specific pages for affiliate products related to your websites, or try combine them into your own sales offering. Do however be vary you don't diminish the value of your products in doing so.