If you want to wear a gaff for any reason, and especially if want to dress as a woman, you better start with shaving your pubic area. Leaving hair at pubic area can be hurtful and can make you uncomfortable in gaff. So better clear and clean the area of hair.
Next step is to tuck your testicles in cavity of your abdomen. Complete the process carefully and if you are feeling hurt, it is possible that you are not tucking your testicles in the right place.
Tape your testicles in the place to secure them. Make sure you do not tape any area behind it, especially if you have not shaved. removal of tape from the hair can be a painful process for you and it might hurt you seriously during the process.
Before wearing the gaff select its right direction. Larger part of the gaff is the front side and smaller and thinner side is for the back side. Also, lie down on the floor or bed to wear the gaff. You first pull it up till your thighs only. If you have chosen gaff of a very small size it will be quite difficult for you to fit in, so make sure you select a gaff that is not too tight.
Before pulling gaff above your thighs tuck you penis in between your legs and wear the gaff. It will be tucked and secured in legs after you wear the gaff. This will leave your front smooth and fit in, and now you can wear any clothes you want.