Here you can find some useful tips.
If you´re on a hurry and need to run a red light, do it on the other side of the street and the cops won´t fine you (has to be a bug, might be fixed)!
Invest your first 3 skillpoints in “good buisness sense” this will give you 20% more income on contracts!
For easy early money do the Street Jobs, it´s just driving back and forth with max. 3 different mashines so you don´t have to learn very much in the beginning.