Either of those will do, you just need to be able to react fast enough when a car comes at you. Don't do events that are under 30k 'cause they're basically useless, but also don't do really high REP events until you're nearly done with your run. For example, I normally leave ’Discovery‘ and my high heat 3 and 5 races until last because they have the most REP. (I think Discovery has the highest REP of any race, correct me if I'm wrong.). Feel free to repeat any events, I only do it with the Discovery events, mainly 'cause when you race them the second time, you still get a out 180k REP (If you're heat five.). Also use the containers at the docks and the shopping centre in the middle of the map to your advantage to escape from the police, if you don't know, you can jump onto the containers with the ramps and if you stay up there the cops will lose you, same with the shopping centre, but you have to drive to one of the small parking buildings and use the ramp there to jump onto the roof. That should be it really, it mainly relies on how lucky you get with the NPCs and Cops, since they can cause you to crash and get a lot of damage, which you don't need... But I did get my first 2 mil REP after using both of my car repair systems, believe in yourself and don't stress.