For me, understanding the mechanics of a real car and how changes effect handling was a big help. While the tuning values don't correlate to real life, i.e. degrees of camber, spring rates, etc, how you change the vehicle is quite realistic. Stiffen the rear = more oversteer, wings & lips add downforce, adjusting brake distribution, etc.
If you really want to get into the nitty gritty, and learn a bit about how real cars respond too, I'd recommend this site:
http://diy-racetuning.net/index.html
Check out the DIY tuning sections linked on the bottom left. Lots of good info on this site.
If you want to get a good enough tune and not mess with it, you have two options. One is to buy a tune off the store front. Many here go this route and have good results. However you will still need to test drive, as not all tunes are good ones.
The second option is to use a tune calculator. You input the car's weight, weight distribution, and drive type (front engine front wheel drive, front engine rear wheel drive, etc) and it spits out some good numbers to start tuning with.
I use a spreadsheet someone on the Forza forums made to get my baseline tune. I then tweak as needed. It works really well for me.
Download the spreadsheet and open in Excel
If you go the more DIY route, read up a bit and feel free to post questions here. We're a helpful bunch and we generally get together every week to race. Racing info is in the 1st post in this thread.
And welcome to AT!
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