I highly recommend buying body armor, always a nice thing to have.

OK, here's the secret. Go to the area shown on the map in purple. Go down to the pond area in the middle, to where a star is underneath the tunnel. The star is for reducing 'cop stars' if you need it. Just hang out by the star with your machine guns and shot gun and shoot whoever comes at you. They'll come in three waves - you don't even get through your body armor before you win the territory over.

There's also a tag spot down by the pond.

Grass comes out - kill him to end the mission. Now you get an income at your house, for that territory!

Mission Passed
Respect +

Grand Theft Auto San Andreas Walkthrough