There are numerous ways of collecting money throughout the Grand Theft Auto 5 game, as long as the player knows where to go.
An easy way of attaining money is by finding collectibles. There are countless collectibles scattered throughout the Grand Theft Auto world. Some of these collectibles include letter scraps, spaceship parts, hidden packages and submarine pieces.
A good resource to use to make finding these collectibles easier is Chop, the Rottweiler dog. Chop is very helpful in searching for specific treasures.
Another feature you can take advantage of is being able to attain collectibles with all three of your characters. You can find collectibles three times and subsequently triple the reward.
Use this map for locations to all 50 letter scraps that are scattered throughout the world. Additionally, the video below explains the locations in a walkthrough format:
Once all 50 letter scraps have been successfully collected, they can be assembled into a four-page letter in which a man named Peter Dreyfuss confesses to a murder. You will then get instructions to kill Dreyfuss in addition to his location. Dreyfuss eventually tries to escape and you can either let him go or kill him. Killing him gets you the Gold requirement.
One of the more difficult challenges in Grand Theft Auto 5 is finding spaceship parts. You can begin to collect spaceship parts after Franklin completes his Far Out mission. Like the letter scraps, there are 50 spaceship parts. Click here to see the exact locations of the parts.