Can you give me some advice on a fearful dog?

Ok so like in august into september, i'm going to board my grandma's australian shepherd. She is a female, and this is the first time i am ever going to board a dog:) I do have experience with dogs by the way because i'm living with a rottie and i helped raised him as a pup and i'm still living with him now. My grandma is going to be gone for a month or more, and i can easily exercise her and feed her, but problem is, she is one fearful dog! She is quite scared of everything and everyone! She might recognize me though because i have cleaned at my grandma's house a few times so she has seen me. The thing i'm worried about is that when my grandma comes to drop her off at me and my family's place, I'm thinking she will be so scared and try to bite somebody or won't get out of the car. I want to help this though, i want to help and train her to not be scared. Do you think you could tell me how to train a fearful australian shepherd? so she won't be scared to death of everything? Thanks:) Oh yeah....i know that i have to be the pack leader to and i already know how to do that. I am pretty young to by the way:) Also, PLEASE do not go telling me that "don't board a fearful dog, have your grandma take her to a professional trainer" she doesn't have the time for that, plus i have already said yes i will board her and i really do want to board her! so Do not say anything like that! just tell me how to train her out of her fearfulness:) and, i've already helped train a rottweiler, so i am experienced:) THANKS:-)