You will need masking tape, a squeegee (or rolled-up small towel), a measuring tape and scissors.
Before you start, put the decal on a hard surface facing up and apply pressure over the graphics/letters with a squeegee, ruler or simply with your finger - this will ensure that the transfer tape will lift the vinyl properly from the wax paper and allow you to transfer to the desired place of application. Follow the procedure below:

1. Fix the decal in the exact position where you want it by placing masking tape vertically in the middle of the decal. This tape is called hinge, because it allows each end of the decal to flip and still holds the middle securely in position. The transfer paper (semi-transparent paper) has to face you, in other words you have to be able to see the image the same way that it's going to look on the car.

2. Once in place, flip one side of the decal and carefully peel the bottom paper (wax paper), cut it off near the hinge and throw it aside. Now the only thing you're holding is the transfer paper with the vinyl graphics on it. Starting from the hinge and working your way out to the end of the decal, firmly press the transfer film to the car surface, using squeegee or tightly rolled towel.

3. Remove the masking tape (hinge) and follow the same procedure for the other side of the decal. Once the entire decal is in place, apply extra pressure over the vinyl graphics, just to make sure they're stuck nicely to the surface.

4. Peel the transfer paper off. CAREFUL: Don't pull 90 degree of the surface, instead peel it off close or completely flat to the surface of the car. If you applied the decal properly, transfer paper will never have enough force to lift off the vinyl, but if you didn't stick it on right, it may take off part of the vinyl graphic.