Correct setups can vary quite a bit between styles of mod - i.e, what works for DTM won't necessarily be great for F1 - and even between seasons of one category, but here is a couple off of the top of my head for the base game:
For tracks like Spa, Suzuka and Montreal, I've been happy with 10 Rear Wing, 12-15 Front, 7 gears with 7th being around '60' and 6th around '53' or '54' and a Brake Balance set to around 42.000:58.000
This is usually fast enough - in a McLaren at least - for driving on Ace if you're comfortable with the track.
Something like Monaco however, I usually have around 18 Rear Wing, 20 Front, 7 gears with 7th being around '56' or '57' and 6th around '50' and a Brake Balance closer to 40.000:60.000.
Again, I find this alright on Ace difficulty.
Of course, what works for me might not work for you - different driving styles/controller setup - but I've got the first of those setups saved as a 'base' setup, which I then modify as needed on a per-track basis.
I generally like as much Front Wing as I can get, to help compensate for the awful steering I have with my 360 controller, but this can cause some oversteer in places - the Esses at Suzuka are just one drift after another, especially as the tires start to die - and I'll try and balance it out with softer rear springs.
I usually have a set number that I like to have for both front and rear packers - although Spa get's quite a few more - and will usually just soften springs or lower ride heights if I've got room to play with, until the point where softer springs make things worse.
I'll try and post my 'base' setup later today.
Hope that helps somewhat.
F1 Graphics Swapper ---
Lensdump - Renders and Screenshots ---
GP4 Performance Generator