The key to turning your established blog into an income generating tool is in traffic. Traffic comes from engagement and getting the word out about your blog in many different ways.
Do people like to visit and read your content?
How many unique visitors do you have on you blog every month?
If you have over 25000 unique visitors per month, logistically, you are in the perfect position to turn your blog into an income machine.
Become a partner in some of the blogger networks out there. Not great money, but $$ are $$. If not, you can do sponsored posts, adsense, sell ad space, affiliate links, sell products, and more.
If your content is that good, sell the content to people who would use it in their business, i.e. I have a company that sells baby accessories and a great blog post that helps her sell baby accessories can be turned into 20 different types of content for her to get her products in front of more people, including a YouTube, Insta post, FB Live, LI, SEO the Shit out of it, a magazine article, a white paper, and more.
Specifically on the SEO side, create dynamic Web rings, on site, and off. SEO all images, video, and content on the page, and link to it from different pages on the site as well as different places on the web like guest blogs and social media help to achieve this.