Ok, first of all, if you have a web space just for commercial purpose, like a site that no point to sell specific products, the ads can became your site protagonist, but, otherwise you have to place them in some ways to not interfere with your primary intent.
Example 1: Put your ads in post or articles, just under the banner for example, in the principal zone above, under or in your text. In this way, the ads will not interfere with the post and at the same time will be well seen by your reader.
Example 2: Link ads, the best place to put them is between your site links, just like any else links on the page. Same thing for the image ads.