Make sure the surface you have chosen to put the sticker on is clean with soap & water, and completely dry after washing. Do NOT use any type of chemical cleaner.
Make sure the surface is close to room or a normal temperature
DO NOT apply sticker on a surface that is very hot (such as a car sitting in the direct sunlight). It will not stick very well.
Once you have attached the sticker to the surface, gently apply pressure the sticker with your hand for about 30 seconds.