To start the bodyweight dip, begin by holding yourself in the top position, with your elbows locked out between parallel bars. If you do not have a dip station, you can do them by setting up two olympic barbells within a power rack.
To begin the movement, take a breath to brace the abs. As you lower your body, keep your elbows tucked to your body. Do not flare them. Lower in a slow and controlled way. Do not drop as you go down.
When you go down, be sure to not go too far down at the bottom, or you will put too much stress on your chest and shoulders and risk a muscle tear. Once you reach a point where you are lowered enough to get a good stretch, explode up by driving through your triceps, locking the elbows out the top. Take a breath to brace your core, and restart the movement.