Just wait till you get to gang wars, if you haven't already. You start by going to a neighboring territory of another gang, and taking out a group of them...after awhile you'll start a war by doing this and a wave of that gang will come at you with bats, after you take them out you've got more coming, this time with pistols. After you finish them off they come at you with automatic weapons. Shit is tough.

Interesting side note, I got my pistol skill all the way up, and it allows you to hold two at once, instead of the regular single pistol. Quite useful.