Hi,
You can search on the forum, there is some articles to start tweaking, or in the past issues of Tweak magazine (available in PDF).
But you're right, tweakers here should make a complete guide for tweaking one day...
another thing to help you, is to find a couple of already pro tweaked bases of diferent models : rookie, TTC, buzzball, etc... so you can use it to compare your own tweaking tries
last thing you can try, is to use Norbert Revells zoomed pictures (available in several topics on the forum) for comparison also ! You see the result on the picture...and try to guess how he made it
better than nothing, no ?
dimitri