How to not be nervous when calling girl?

just chill for a minute then just call her up and say hey then afttr she says hey be like watsup.... then aftr she ansr ask her out or watevr then just talk about wat comes up....if u ask her out and she says she cntt or no just be like o ok maybe some other time. then just finish out the conversation. if she dosnt ansr dnt leave a loong message or just dnt leave one at all... it would help maybe if u textd her and be lyk r u busy... if she dnt ansr ur txt just chill. shes prolly busy