firstly, do a good make up and make sure you dont have a bad hair day. secondly, find a place with good lighting. thirdly if you`re using a DSLR, adjust the ISO and composure so that your skin tone looks good.
and then if you have a camera stand, use it if not just put your camera on something. use the timer!
then.... chee-kek! your picture is out! take a couple to choose from!
and then i can only hope that my picture turn out nice. try different outfits too. i mean, if you look nice you`ll be happy yourself, apart from the need of sending it in for application.