I learned so much about the commands that intimidated me by playing "Oh My Git!"[1]. It's an open source game that presents commands as quick-to-understand concepts and lets you experiment with them by using playing cards on the visual rendition of a repository. I was honestly surprised nobody else mentioned it here, maybe it's not that well known.
Of course it's not completely accurate all the time in its descriptions but it sure helps understanding the underlying workings a bit more, and it pushed me into actually reading the manual.