Connect with your readers first before you write your post. People want to know who you are and why you're qualified to teach before they'll open their hearts and minds to listening to what you have to say.
https://thedocmag.com/ Finally, once you get into the heart of the content, give it your 100%. Give them the best quality content you can and don't worry about selling. The goal of the article shouldn't be to sell to someone on a click-through, but to write an article that's so good that they'll seek out the link in your bio box.
Make people want to know more by giving them a taste of what you have to offer.
That's how to approach blog and site owners and offer to do a guest blog post. It's not difficult. All it takes is commitment and persistence.