by Davo Smith.
This page (and the pages linked to it) give an overview of good practice in Moodle coding: http://docs.moodle.org/dev/Coding
An alternative is to contact one of the official 'Moodle Partners' and ask them for a quote to review a plugin for you (my employers Synergy Learning are one such partner, others can be found at http://moodle.com ).