It doesn’t mater where you get your templates from. Once the site is up and runing you can apply to join the various advertising and affiliate programs. BUT – and this is a very big but – you will only be successful if you have A LOT of traffic and can get your site to appear on the first page of the search engine results. I learned all this the hard way through running my own website about bipolar disorder and making a living off the advertising revenue. It is tempting to go with the cheapest templates and webhost you can get, but in the end it may be wise to invest in templates and webhosting where you get a lot of help with serach engine optimization and building lots of traffic – why build a website when you can build a business? Good luck with it!. The links below are to my site and to the host I use, who saved me a lot of time and trouble and got me earning money fast.
All the best, Sarah