The Association Croquet pages contain some coaching and playing tips and are intended as a reference for ideas for players to try out for themselves.
There is also a 1-day course on Short Croquet.

The Golf Croquet pages contain links to three coaching manuals (Beginner, Intermediate and Advanced) and some pod handouts which may be printed or downloaded.

We have played Pirates Croquet at Taunton Deane and evolved
a set of rules for our own use.
They may be downloaded here for use at other clubs.