Hi & welcome to YT!!!
I have found that the best thing to do is find a picture of a cut you like and take it to the groomer with you. The usual term for what it sounds like you want is a "puppy cut" but you will want to be specific as to how long you want the hair to be when they are done. If you want anything longer than about an inch you'll need to find a groomer who will hand scissor, instead of just use clippers.
I don't personally like the hair as short as they do it when they use clippers, but to each their own
Just make sure to be specific about the length, or you may end up with a baby shaved to her skin
(you'll see lots of horror stories in threads in this section). Also, make sure to let them know if you want to keep a topknot and if you want them to clip the hair on the nose and by the eyes, as they may not "assume" correctly.
Good luck!!