How to customize a face? (Docs don't help)

[Da Witch]

When it comes to the question of how to customize a font face, I find
the Emacs documentation not helpful at...  I remember that in the
past, customizing faces has taken me hours of trial-and-error and
fruitless scanning of the docs.  I see now that this confusing
situation has not changed...  For example, I've spent about 1 hour
this morning trying in vain to find out how to determine the name of a
face I have on the screen (so that I can customize it).  If I do M-x
customize-face, and I'm prompted for the name of the face to
customize, the default answer is "all", which is much less helpful a
default answer than the name of the face the point is currently on.
The mode I'm currently using has about one dozen faces, and I can't
tell from their names what most of them correspond to.

Thanks in advance,

h