This is something that I've had in mind since long time ago, to have a MathJax tutorial for first time users.
Users that never have write using MathJax.
And instead of seeing the whole and giant page MathJax basic tutorial and quick reference, that honestly, well a first look at it it's overwhelming maybe?..
To see only a page where specifies math commands (say up to 10-15) that you commonly see in the first years like:
If you type
$\int$will display $\int$
and so on. This looks ugly, but it's just to clarify the idea:)
And after this, to tell them about the link MathJax basic tutorial and quick reference