Ok... If Google is not displaying relevant ads on your site, you can try several things. But we will discuss just one tip... Something that is often neglected...Here it is...
Name your domain or directory according to the main theme
of your site. For example, if you are building a site on Wheelchairs, have a domain called www.wheelchair.com. Now, certainly www.wheelchair.com will not be available but you can have something like www.wheelchairworld.com or www.wheelchairshop.com or something similar.
You get the point right?
If you already have a generic domain like www.tomdickharry.com, and you want a page on wheelchairs, don’t create a directory like www.tomdickharry.com/wc, instead you should create something like www.tomdickharry.com/wheelchairs
This will tell Google that your site or your page is about wheelchairs, and it will serve targeted ads. This seemingly obvious tip is often neglected. Now that you know, make sure you give proper names to your domains and directories!