The general criterion of starting in with confidence is not really
reliable at all.
I think most new contributors with experience in other media would
look around WP a good deal before they started editing. I certainly
did, not wanting to appear like a utter newbie. The general criterion
of knowing what to do when you come here is not really that reliable.
Even the use of abbreviations can be picked up fairly easily; other
forms of writing on the web use similar methods, and its just
necessary to learn a few new ones. The sort of markup used in WP is
very simple--a great many people know this already--I found my problem
was to unlearn the parts of html that weren't implemented.
And I know many young teenagers who can catch on to this sort of thing
a lot faster than i did.
David Goodman, Ph.D, M.L.S.