Another great way to find topics to blog about is to just ask your peeps.
You can set up a form so your readers can submit questions and you can answer them on your blog.
I like using Gravity Forms and JotForm for creating all kinds of forms that I can install right on my WordPress site.
And often, I use Survey Monkey to do more in-depth research into what my readers want and to find out what they think.
You can gather all kinds of information and then write about it on your blog.