Well, dude guides as such are hard to come by and normally you can research all concepts online... Maybe, just maybe, one day I may put one together...
Even though it's for Forza 3, the telemetry is pretty much the same for Forza 4. It'll give you a good idea of what settings to change based on all the **** that is displayed.
Well there you go.... looks very comprehensive too...
But dont be discouraged if nothing makes sense at first... Just know that getting that set up just right is nothing short than a "black art" skill (as one site puts it)...
this is the tuning tread that I've been using off the Forza forums, very comprehensive and covers a lot to topics if you have the time to put it into practice