I place one adsense block in the sidebar which is only shown on the homepage, the rest will be inside the content to the left. I used to make blog posts that were the exact match as the keyword I wanted to rank, for example if I wanted to rank for registered nurse, than the title of the post would be registered nurse. Now I look for niches that have potential to become large sites, so I stick to medical careers. The medical field pays well, normally I will see 2,3 and 4 dollar clicks. Each site only gets between 80 and 125 visitors a day yet they all make 100.00 to 150.00 a month.
I only backlink the homepage using article marketing ,social bookmarks, forum profiles etc. I don't even try to rank these sites for any keyword, all my traffic come from long tail searches. I use google analytics to see how people got to my site than I use those search terms as post titles. For example , Do I have to be good at math to become a registered nurse, can I become a registered nurse with a g.e.d. , how do I become a registered nurse if I already have a degree in health science
The only thing I do to make a site is search for a medical career, research what kind of degrees and training is required , think of a bunch of questions I can write about and that's it. Each site is 75 to 100 pages.
Never use the type of links described above ( article marketing ,social bookmarks, forum profiles etc) they will most defiantly harm your site.