Good LaTeX tutorials?

I’m revamping the Tectonic website a bit and would like to provide some pointers to a few good LaTeX tutorials — at the present time, I don’t think that most Tectonic users will need them, but I’d like for us to be welcoming to folks who are truly beginners. (After all, one of Tectonic’s selling points is that it’s easy to install and use, so I want it to provide an all-around great experience for those folks.)

The problem is that I haven’t needed a LaTeX tutorial in a long time so I have no idea what the good ones are. Does anyone have any suggestions?