In the past, I used to write for search engines. When I searched for something online and did not find appropriate content on the topic, I would research on the idea and create a blog post. This strategy helped me to get higher ranks and brought me good traffic and revenue. But these days I mostly write about the topic that I am passionate about. I do not care whether the topic has search value or not, the only think I make sure is that the topic is not overly saturated. However, when I write for clients, I write on the topics I am hired to write for.