The "new ticket" page should contain good advice on how to write good tickets.
The text could be something like,
Hi, and thank you for helping to make Tor better!
Before you post your ticket, please check it against this checklist to make sure it includes all the info we need to figure out how to solve the problem.
- If there was an error message, please make sure to copy it exactly.
- If this is crash bug, or there is an assertion failure, or Tor just won't start, make sure to include a stack trace if possible
- Are you logged in using an account with a working email? of course, we are fine with anonymous bug reports, but if we questions for you, it will help if the bug tracker has some way to contact you about them.
I don't think that's the sum of what we want to say here; it would be nice to be terse but friendly.
How to do this? A little googling turned up http://trac.edgewall.org/ticket/2021 which seems to talk about introducing the relevant feature, and and http://trac.edgewall.org/wiki/TracInterfaceCustomization , which seem to give instructions.