That is easy, find the inspiration in the things that interest you, things you already have some knowledge of and allow the synchronicity of learning to move you to the edges of those subjects. Explore the fringes of those related topics, research them and familiarize yourself with them. Investigate, read and use critical thinking to find ideas about your interests that you haven't explored before.
The writing is the hard part, yet it begins with one word, just as any journey begins with one step. For me writing helps me to clarify my thinking, of course I write about topics most writer won't touch if you paid them but I do not write to prove anything merely to plant the seed of knowledge . . . what you do with the information is your business.
Look at all the interesting topics that comprise our world news, read an article online and then ask yourself the questions the author didn't answer . . . you now have a topic and a reason to research, answer your own question in the form of an article.