Go to any airport. Look for a yellow arrow at the entrances of the airport where you can buy a ticket to another city. Buy the ticket and start the flight. Do not press A and skip the flight. Wait for the airplane to take off and get high in the air. Press Y and CJ will jump out of the airplane with a parachute and begin skydiving. When you want to open the parachute, press B and float down. There are also other places you can skydive, such as the tall building in the Downtown area of Los Santos, and off the top of Mt. Chiliad. Additionally, to get a parachute very easily, get into any type of flying vehicle, except the Jetpack. You will instantly receive a parachute. If you fly high into the air, then jump out of your plane or helicopter, the parachute will automatically be switched into your weapon inventory.