I still battle with my inner dialog about "not being an expert" at anything. This is something I get caught up on but all you really need to be is more knowledgeable than your target audience. So sell something you already know to people who want to know it. There are still people out there that are basically beginners in web development. There are people one or more rungs down the ladder from you. You don't have to sell them some complex guide to intricacies of angular. How many non-technical people want to sell things only? People serve them all the time.

One example I heard recently on a podcast was cssanimation.rocks. Basically his thought process was: I want to teach people something regarding CSS. I can't teach people ALL of CSS in a book (too much work). I like making animations. I'm going to focus on practical animations (forms, list boxes, basically things all sites do). He started posting some useful blog posts that taught people some of the basic concepts and captured emails. Now he has paying subscribers to an email course.

Disclaimer: I fail to do everything I'm telling you to do.