I keep all of them on when racing online apart for brake assist. Braking just comes with practice. Try offline Time Trial mode from padock. Choose a car and track and load into the pits, when your in the pits access the comp screen sat on your car and select the car setup option. (last option on the right)
From there you can custom setup your car, (try some the setups from the link I posted) when your done save the setup and go out and practice. Set a time and try and beat it.
When you go online select car setup option again and load your custom setup for that track.(custom setups wont guarantee you will win the race, but they give you a fighting chance).
Other then that all I can say is practice, practice and more practice, Also you can try online grand-prix mode you get 15mins of quey free time to learn the track, sprint mode is full of idiots and is harder.