There’s this girl that I want to dream about.
Does anyone have any tips for dreaming about something that you want to dream about?
Do you want it to be a LD or ND?
VILD works nicely if you’re going for a LD, otherwise autosuggestion. 
why do you want to dream about this girl
I agree with Wolf, try using VILD. Don’t get frustrated if it doesn’t work on the first or second night though. Autosuggestion never seemed to do it for me, but you might like to try it! Good luck!