* Contact your nearest user group to see if they are, or know of anybody already planning on running a TestFest in your area
* Find a suitable location and choose a date within the TestFest range
* Check that a mentor will be able to assist with your event
* Publish details of your event somewhere (Usergroup wiki, homepage, blog, etc.)
* Anounce your event:
** Local usergroup news feed
** Calendar entry on php.net/cal
** Announcement to php-qa@lists.php.net
** Any other blogs or relevant places you can think of
* After a short while, check that your event has been approved on php.net/cal and is listed on http://wiki.php.net/qa/testfest
* Some time before the event (somebody help me here) you will be contacted with details of Subversion access for your group
* Get a list of names of attendees (and email addresses) in advance
* Grant access to SVN in advance (testfest.php.net/testtfest.php)
* Limit the numbers if you don't have a reasonable ratio of mentors to attendees (suggested max 1:4)
* Mail attendees the day before to remind them to bring laptops (and possibly power supply and ethernet cable)
* Ask attendees (with any other OS than Windows) to try and download and compile PHP in advance (to check that they have a build env't)
* Make sure that the location has network connection (wireless/ethernet)
* Pick an area (extension) to test in advance and let the attendees know so that they can do some preparation. 
* Mail the QA list to say what extension you are looking at so that you can co-ordinate with other groups if they want to work in the same area
* Work out in advance which test cases are missing and have a list of then ready for people to work on
* If you pick something that has pre-reqs (eg database, libraries) prepare some samples and make sure that people know to install the pre-reqs.
* Either at the event or in advance have someone give a short talk on the extension and show example of how to use it
* Be prepared for network failure - have copies of PHP source, Windows builds and docs on a stick.
* Find a local source of beer for *after* the event