I finished that one first attempt. It is hard though, just gotta cap anything that moves. Grenades work well when the game puts ya undercover. You might want to go to the guns dealer & get a vest before that mission.
I also found the Heliport. Its located on the map too for easy nav.
Right now stuck on the mission where you go to an abandoned hospital to collect coke which is ofcourse guarded heavily but thats not the best part. I got through all the dealers, (15 or so), got the coke, & than you are completely surrounded by S.W.A.T. Happy, Happy, Joy, Joy. I have 2 attempts at this mission.
First, (pure luck) made it out of the labyrinth hospital & actually made it to a vehicle before getting shot down cause the car was indeed locked.
Second attempt, didn't even make it out of the labyrinth err.. mean hospital.
edit
Forgot to mention, I took the helicopter all the way up & jumped out when I was above water. Apparently you can free fall thousands of feet into water & live.
