Almost anything about Wordpress. -Getting Started -Finding the right themes & plugins -Search Engine Optimization -Editing CSS, HTML,& PHP -Security & Backups -Finding a good web host Note: I currently only answer questions about single user Wordpress. I don't answer questions about Multi-User.
I've built several personal and business websites with Wordpress, as well as a few others for colleges. In my opinion, it's one of the most powerful ways to make any website (not just blogs)! I've downloaded and used over 400 plugins, and read about many others. I always download free themes for my websites, then heavily customize the CSS and PHP until it looks unique. Over the years I've become an expert in Wordpress because that is all I've ever used to create my websites.
Personal experience using Wordpress since 2007.