The three main ways of making a profit from blogging are:
Advertising- This is the traditional method of making money, but it is still effective today. You could either sell advertising space, or you can place ads on your blog with Google Adsense, or any other advertising program. You are not going to make a lot of money from Adsense even if you own a popular blog. Usually high traffic blogs only make a couple of dollars a day. That is enough to cover a part of the cost of running your website/blog. If you still want to use this method, then I would take a look at the Higher-paying Adsense alternatives.
Affiliate links- I never put affiliate links on my blog, but some blogs do. If you use them in the right way, then you can earn a bit more than you would from traditional advertising. Just don’t cover your blog in affiliate links, because that can make you seem desperate. Also, remember to clearly label an affiliate link. It can be as simple as (affiliate link). I recommend the Amazon Affiliate Program.
Selling a product- This is the most profitable method because your physical product is going to be worth more than a few clicks on advertisements. If you have the time and resources, then I would definitely consider this method. Some products that you can make are ebooks, print books, or just anything else that your blog readers could benifit from.
When you have a service like Adsense on your website or blog, to display relevant ads, they crawl your website looking for keywords, and then matching those keywords with relevant ads. That said, to get the ads to be more effective and of interest to the people visiting your website, then you should update your content and keep it fresh.