About a week or so before the prom/dance, approach your crush at an appropriate time when you know he/she isn’t busy or upset.,
Simply and calmly ask your crush, “Would you like to go to the prom/dance with me?”,
Wait for your crush’s response.
Make sure you talk to your crush in an empty area with none of his/her friends around, or your crush might feel intimidated.
If you find your crush with his/her friends, polite ask your crush, “May I please talk to you alone real quick?”
If you’re already scared by this step, tell yourself inwardly that you have twenty seconds of insane courage to do whatever you want and that it’ll take one second of humiliation to get nineteen seconds of pride for your bravery.
If your crush agrees, you can go shopping.
If your crush declines, do not freak out. Still keep maintaining that relationship with your crush and treat him/her nicely. It still has its chances of blossoming into a romantic bond! Keep in mind that if you take this calmly, your crush might change his/her mind.