How to ask my mommmm?

whenever i want somrthing or want to do something that i have to ask my mom for permision or whatever, i can never get it out of my mouth even if its something small like can i heve my friend sleepover. and whenever it does come out i always start it the same way "Hey mom?' and shell be like " yeah" and ill ask the question really nervously. i want to ask her if i can sign up for my school cheerleading team and i neeed to no how to ask her.