I've only done a few races, the occasional repo job for Simeon, a few drug collections for Gerald and one for Trevor. My stats are still pretty shit although I'm nearly Level 16 now. Really weary about doing a Heist when my character is so weak. I've also robbed every store Easy XP and money. The more you do in one sitting though; the higher your wanted level became so I could only do 3 in a session before I hit the 6 star rating!