Im painting my room this weekend but I don't know what color?

Heres a discription of my room: its a basement room with 2 big windows i have a shelf going through the middle on 2 walls I also have one big wall and a closet on the right. my carpets (which are stayng) are light grey and my ceiling is going to be dark purple. im thinking max of 3 colors one on top of my shelf and one on the bottem plus by my closet also have one accent color (im thinking pink) for big wall and closet. im 18 turning 19 and plan on living here till i get out of univeristy in 5 years but i do have a kiddish personality i was also thinking blue, green and pink but with the purple ceiling i was thinking it might be too busy... give me your suggestions :)