There are many ways to improve your skills in GTA 5 so find out all the tricks.
You can boost your shooting skills and strength to 100 in as fast as 10 minutes if you use the bus trick. Purchase a big amount of pistol ammunition and look for a bus nearby. Jump on top of the bus and tramp on it while it is moving. It is important to move back and forth, otherwise you might fall off the bus. This will eventually increase your strength stat to 100.
You can boost your shooting skill stat by shooting down the middle part of the bus until it reaches 100. The bus will take the bullets but will not be destroyed. An easy technique to boost your stealth stat to max is putting a rubber band around every analog stick of your controller. This will keep the character walking automatically and after 100 minutes, your stealth skill will be at 100 as every minute in stealth mode ups your stat by one.
Don't you want to get a head start in a race? Do so by holding down the L1 button for PS3 players and LB for Xbox 360 users while on countdown before the race starts. This will give you a headstart in the race and allow easy victories later on.
Xbox 360: Y, Right(2), Left, Right, X, B, Left.
PS3: Triangle, Right, Right, Left, Right, Square, Circle, Left
Xbox 360: Y, Left, Right(2), X, RT, RB
PS3: Square, L2, R1, Triangle, Left, Square, L2, Right, X
The code can be entered up to four times to boost its effect. The fifth time will disable the code.
Xbox 360: RT, A, LB(2), LT(3), X
PS3: R2, X, L1, L1, L2, L2, L2, Square
Each time the code is entered, it will rotate through sunny, cloudy, clear, smoggy, thundering, rainy, overcast, clearing, and snowing weather.
This cheat will spawn you in the air for a skydive free fall. Hold the Analog stick and glide for quite a while. This will not allow you to use the parachute, though. You will often die at the end of a free fall. You can survive but with little health left. Do a direct vertical faceplant to survive and if you can pull this off, it will be very useful for fast travel around the map.