Read manga: I Want To Know Everything!

manga
Summary:

The main character is a girl who everyone mistakes for a highly experienced flirt as she gives the most advice to girls on their relationship problems (and because of her cute looks) The truth is, she's no more than a whimpy novice who hasn't even experienced her first kiss yet! (Credit for her advice goes to teen magazines and much research) Her pent-out frustrations were overheard by the school's most outrageous flirt and those two strike up a deal for her to take up lessons to advance in experience...!