Easy cash on Mt.Chiliad
Here is how to get a few grand at a time on Mt.Chiliad. Ok, get to the top of Mt.Chiliad and hop on the bike they place up there. Depending on the time, a race might start. If it doesn't just wait around up there until it does. When the race down the mountain begins, look to your left and there should be a flagpole with a ramp next to it. Forget the race and go off the ramp doing flips and spins. You will get teleported back on the mountain but with an insane stunt bonus of a couple hundred dollars! Repeat this process until the race ends. Then wait around for the next race to begin!
Go into a strip club and stand in front of the stripper when the people watching puts money up there CJ will get it since he is where they put the money
Easy Pistol Ammo/Weapon Skill
Get to 3-4 stars and go into A Cluckin' Bell. (I used the one across from the Paint n Spray in Los Santos.) Go into the room with two doors. Sit in there for a second after the doors are shut and go back outside to the lobby. There's new people in there. If you have 3-4 stars, Policement will appear, but they don't attack. Kill them for pistols and easy weapon skill.
Get a pilot license without going to pilot school!
Hop the fence to the Los Santos airport, hop in the SHAMAL, and keep flying it for about 25 minutes. In the upper right hand corner of the screen, it will say to keep practicing to obtain a pilot's license. Fly for about 10 minutes more, and you will obtain a pilot's license and have access to all airports!
Win Chiliad Challenge easily
When doing the Chiliad challenge let the other racers finish before you. Then stop before hitting the final marker and get off. Next get out a sniper rifle and snipe all of the competitors. After each snipe you'll notice your position is going up. If you snipe them all you will be in first place.