What to post? You can post anything
inspired by Alexey Guzey’s Why You Should Start a Blog Right Now (archive)
It’s discouraging to browse the internet when researching things to write about. You’ll find amazing projects and posts by people smarter than you and it’s likely that you’ll find the very exact thing you were thinking of doing, but of course better-executed and well-written. It’s easy to walk away convinced you should write nothing because any attempt will be inferior, embarrassing, and a waste of time.