First, you need a place to stay around here, so you get a wardrobe. There are several buildings that are only $20,000, which you can earn in a short period of time doing the trucker missions. Then put on your uniform and go over to the hotel. It's near the pizza spot in the Financial district.

When a car with a blue arrow comes over, hop in it before your buddies do and drive straight across to the street. Take a hard right down into the garage and park in the indicated red spot. Now run back up to the valet area again. If one of the other guys gets a car, you can't kick them out. You just have to wait for the next one to come along.

You have a time limit (2 min) for each set of cars - and you get a bonus amount of time if you don't hurt the cars at all. As soon as you finish the first set, the timer starts counting immediately for the next set. Having your run skill maxed out REALLY helps with this. You can get up to a minute bonus on a given car and since it takes less than a minute to park a car, you should have an easy time as long as you don't damage each car. Look left out of your car window as you go down into the garage to see if the spot is in that first area on the left.

Level 1 - 3 cars ($100 tip)
Level 2 - 4 cars ($200 tip)
Level 3 - 5 cars ($300 tip)
Level 4 - 6 cars ($400 tip)
Level 5 - 7 cars ($500 tip)

After level 5, the hotel is now an "income earning property" and you can go back there to pick up your cash at any time. It will only hold up to $2,000 - so check back often :)

Grand Theft Auto San Andreas Walkthrough