Eventually you will get a chance to higher henchmen that can go out by themselves and do jobs for you.

Driver-basically it is stealing cars and dropping them off

Enforcer-basically the job is going out and destroying unrully gangs for Tony.

Assassin- Your job is to take out one particular target (your target will have a knife floating about their heads, you may have to get in close)

Arms Dealer-this guy doesn't do any fighting (no side missions), he hangs out at the mansion near the garage and you can buy weapons off him, the weapons go staight to your weapons locker in your house or in your car.

Boat Pilot- he brings your boat around (very useful in tight situations), no side missions though.