There is a hierarchy for spending your Race or Die Respect Points, which means that getting the free money for ten Race or Die Respect Points. This amount of money changes depending on how far in the game you are, and since you will want to find money without leveling up early on you may want to use this. After that will be to get more friends, but since Race or Die has a Friend Code system this should not be the first place you go.
The Race or Die Friend Code system usually makes adding friends to your account relatively easy. Instead of wasting your Respect Points on more friends you can just browse online forums for Race or Die Friend Codes. Only resort to this if you are having a lot of trouble with Race or Die Friend Codes.
If you are farther in the game and want to level up you can use the Race or Die Respect Points to refill your energy bar, but only do this if you have a large energy bar. Normally using Race or Die Respect Points to heal yourself is not a great idea, but since it only costs a single Respect Point it can be used on occasion.