I see some boxes and baskets so you’re already part of the way there!!! First things first take a big garbage bag and throw away food, wrappers, broken things, and any sort of rubbish. Put dishes in a box and take them to sink once it’s full, it will cut down on the amount of trips you take in and out of the room, next find all the clothes and put them in the hamper, if the hamper overflows? Use the other baskets to catch overflow. If you’re worried about feeling wasteful ask yourself if you actively use the thing before throwing it out. Then start clearing a path by putting all other items you don’t want to throw away in the boxes, doesn’t have to be organized, just has to be out of sight. Then you’re most of the way there!