During Chapter 5, go to both the wharf and warehouse 12. Beat all of the thugs with weapons, then go to the storage room to rescue her.
Unlockable: Jason G:
When you're going through Chapter 4, make a visit to the gas station. You'll confront 3 gang members. Beat them, and a cutscene with Jason. Beat him down and he'll join your crew.
During Chapter 2, beat any of the five Fatimas Saints. Then go to the police station. Lola is locked-up in the cell area. Rescue her and she's yours.
During Chapter 4, go to southside park. Raven might confront you when you're there. If he does, beat him. If you succeed, he'll join you're party. But you only have one chance to make it work, so fight good.
Once you pass Fatima's Saints, you'll have repeated confrontations with Norma through-out the game. You must beat her every time in order to finally add her to your team. It will happen after you finally beat her in Chapter 6. She''l call you on your way to the hotel zone, and ask you to meet her at the basketball court. Whoop on her until her pride guage depletes and she'll join your team.