You want to be certain that thousands (if not millions) of other people share your enthusiasm and interest in the topic and will pay money for products and/or services that you have to offer in the niche from time to time. Even if you’re not interested in making money from your blog, I am assuming that you at least want other people to read it – yes? Then the same rules apply.
Perhaps the most popular network for placing these types of ads is Google AdSense. With this program, you do not need to be in direct contact with advertisers; you simply place the banner on your site, Google chooses ads relevant to your content, and your viewers click on the ads. There are countless similar programs available if you find that AdSense doesn’t work for you, such as Chitika, Infolinks, and Media.net.