An easy way get money is to go to an ATM and cause a traffic jam to the surrounding area. Wait for someone to take money from the ATM and then kill them. Take the money they dropped on the ground. Run a short distance away and come back. The money should reappear on the ground. Repeat this as many times as you want. Kill more people accessing the ATM and their money will also reappear.
To get easy money, go to an area where there are a lot of people and dial the "Spawn Jetmax" phone number cheat. Position yourself so that the boat spawns above the people and kills them without raising your wanted level. Pickup the money dropped by the people you killed and repeat as desired.
Steal a Securicar and blow it up to earn about $1,000 from the piles surrounding the wreckage. To do this without getting a wanted level, drive it and get it damaged until it catches fire and explodes. Do not attack it with a weapon, or else it will result in a two star wanted level.
Park an armored truck in your parking space. Blow it up to take the money. Make sure the blown up truck stays in the parking spot. Then, save the game. Load the game. The truck will be brand new in your parking spot. You will keep the money each time you blow it up and save the game.
Go to Broker or Dukes and find an armored truck. Stop the truck by standing in front of it or blocking it with a car. Then, take out a rocket launcher and blow up the truck. Enable the "Remove Niko's wanted level" code. Collect all the money around the truck.
Go to the strip club and kill the strippers there. Each one drops about five or six wads of cash. Note: All the guards will attack you.
Go to the Modo clothing store and kill the cashier. Go behind the counter and stand by the cash register, then press LB to open it to get between $30 and $200. You will also get a one star wanted level for killing the cashier.
Go to any Internet cafe and walk to the snack bar. Get behind the counter and stand by the cash register, then press LB to open the register and take out the cash. You will usually get $30 to $200. You will also get a one star wanted level for doing this.
After completing the thirty text message car deliveries, you can spawn Turismos or Super GTs in front of the garage and park them inside to make $11,000 each time.
Walk into any clothing store and take cash register without getting a wanted level.
Complete Brucie's missions until you go into the police computer. Once you have done that mission, look at the "Top 10 Most Wanted" section and select a victim. Make a note of his name, then search the "Police Database" by name. Enter your victim's name and choose "Search" to have the criminal's location placed on your map. This is the easiest and the most fun way to get money.
Go to the Alderney State Correctional Facility and get inside. Then, spawn a car or motorcycle and have the "Remove Niko's wanted level" cheat ready to activate. Kill orange dressed prisoners by hitting them with your car as they usually drop lots of money.
Complete all thirty car deliveries to Stevie to receive a text message informing you that any car except emergency vehicles brought in will be sold and you will be paid a reward. There is no limit on how many times this can be done.