I have to discuss about Social Bookmarking Sites because of the improvement of our website page rank as well as Keyword Population through your back links. If you want to earn money through your website which is related to your niche then you have to add your websites with social bookmarking websites then it will be rocking with your keywords and fight with competitive keywords. I hope it will be the best way to optimize your website.
Also you can add your websites in web directory like DMOZ and addurl.nu which is very useful to improve your pagerank as well as keyword popularity. You should have legal resources for your websites which is getting proper way of traffic to your websites through Search Engine results.
Search Engine Submission also help you to improve your web page back links which is also improving your search engine based results to your websites in your niche keywords. I hope you will be getting into proper way seo then you will be dominating your competition area. So you can get the best results to your websites to make money.