Hit the Courier/Walkthrough

Get a fast car and then quickly drive to the meeting in some docks at Viceport. There you will see the receivers, a group of armed women, first of all kill the two women wielding SPAS-12s, then kill the one with the M4 Carbine and then the ones with Uzis. Next, move on along the docks until you come along more armed women, kill them and (if you drove extremely fast to the meeting), the courier should be landing in a Maverick helicopter.

Now quickly, pull out an assault rifle (since she's wearing armor) and gun her and her escort down, before they reach their getaway car, since if they get on the car you will have to snipe the courier dead, because if you blow the car up with the courier inside, the plates will get blow up as well. Once the courier is dead, pick up the plates and run for it, then get in your car and drive away, now just drive back to the print works and deliver the plates. Mission accomplished!