Spray the shirt with water
First of all, water the shirt with the help of a water spray before you iron it. This would make sure that the shirt is pressed properly and that no wrinkles remain when you finish ironing the shirt. Make sure that you do not add too much water to the shirt as that would damage the fabric. If you do not have a bottle spray, sprinkle some water with your hand equally.
Set the ironing board ready
Secondly, set the ironing board ready and make sure you turn your iron to a medium temperature. Ironing the shirt at a higher temperature will damage the fabric and there is also a chance of burning it.
Iron the shirt
Start with the sleeves. Carefully iron the sleeves on both sides and then place the shirt in a vertical position to press the shirt body. Iron the body and the sleeve seams before you iron the collar. When you are done with the front side, move on to the back and carry on with the same task. After ironing the shirt body from the back side, press the collar. First open the collar and press it and then fold it to iron it again.
Use spray starch on collar and cuffs
Apply spray starch to stiffen the collar and cuffs of the tuxedo shirt. Spray a reasonable amount and iron the areas after placing a dry dish towel over them. Do not iron the areas directly as that would leave stains on the shirt. Once you are done with ironing the collar and cuffs after spraying the starch, the tuxedo shirt is ready to be worn.