Most Helpful Girl
Well the guy I am dating right now I walked to his car with him on the way out of school and we were just talking about plans with friends and he just asked if i wanted to go set sushi (he knew I liked sushi because we had talked about it) sometime just the two of us... I said yes of course!
He has told me since that he never actually planned in asking before hand which was good because he said he would have probably been to shy or nervous if he had planned it ahead...
So my advice is just do it causally when you two aren't around too many people and let it come out naturally.
Good Luck! I hope it works out!