A little tips for you: Join a team you will gain Gear Credit and do hotlap challenge till you have ennough to buy a 60 pi team car.
Note: Team are permanent and you can't change team once you have choosed one.
In hotlap go slower on the first lap but not too slow you must be 5 or 10 seconds faster than the goal in the Botom-left corner of the screen.
First lap go slower but beat the goal to gain your first 200 Gear Credit once you done that all you have to do is beat your goal by miliseconds to gain as much as you can on that track then change track and repeat these steps.
Enjoy the game! :)
Use the 25 PI free car to do it, it will be usefull if you wish to do it later with an other car.