i too am a DFGT rookie, got it 2 days ago, maybe 10-15 hrs on it at most (and a good majority of them were a-spec/dream car champ/indy/FGT just so i could get used to the force feedback and such.
today, i started messing around in practice and having great improvements. i used the settings straight out of the box, found a lotus 111r '04 in my garage, put racing exhaust, oil change and racing softs on, took it to Tsukuba with the ghost on and started putting laps down. takes lots of the frustration of the AI out of the game when your only racing yourself. you can actually 'see' yourself getting better or where you can improve yourself at. so far, ive trimmed 15 seconds down and actually put in a lap that i could'nt beat with my controller.
after about 2 hours of that, i read this thread and found you can adjust it (who woulda thunk it?), decided to play with that alittle to try to get the "user break in" period to speed up (yes, im impatient). turned the feedback to 3, and power assist on with amatuer mode on and seems easier to control, but my laptimes are staying around the same. seems it might actually be easier to get used to using the stock box settings... just my two cents.
good luck!!