There is usually a hint in the quest book or on certain girls on what to do next (i did all the content like a month ago so i'm kinda waiting and don't remember)
For anyone with this issue still, there is no order simply add all the girls that you haven't maxed to quick view and check there for their hints after you reach the required number, can also be checked from going into the girls menu and clicking on them but this saves you going into menus.
