While trying to take over gang territory, take one of the datable girls with you. Between waves of enemy gang members, if you give your girlfriend a gift or kiss them, the enemy gang members will freeze in place. They won't notice you around them, but if you throw a grenade at them or otherwise threaten them, they'll un-freeze. Grab a rocket launcher or molotov and you can take over territory really easy. Also, this would give you a chance to get the health and armor pickups in the area without being shot at.