Placing AdSense ad unit in blogs is generally the same with placing AdSense ad unit in other sites, which is to focus on places where visitor's eyes linger the most, though is a bit more difficult. This is because of the almost similar page format for most blogs and by being a regular visitor makes a visitor ad-blind, which is the predictable nature of the ads make the visitors (maybe unconsciously) ignore the ads.
So, instead of just normal strategy in AdSense ad units placement, add the following tips to the list;
This works in the main page or the category where the blog post snippets are displayed. Visitors who go through your posts will be reading your (banner) ads in between the posts. This can easily be achieved by some AdSense related plugin if you're using Wordpress.
If you don't have much links yourself, you can just use AdSense's link units at areas where links are normally placed, such as below the blog's title, or at the sidebar.
The most popular blog platforms all provide search functionality. If you run your own blog (rather that using free hosting such as Blogger or Wordpress.org), you have the option to replace it with Google's AdSense for Search. You might earn some money from the ads displayed in the search result page.