clean and tidy my room (and keep it that way)

My brother is 17, and mostly stays at his mom’s house. So I got his room.
It’s bigger which gives me more room for all my junk.
I am in the process of going through boxes of crap that I dont need. I want to get rid of a lot of it so I can get some money and buy NEW things for my room.
But once I get the boxes empty, my room should be a lot cleaner.
Now the hard part is keeping it clean. I dont know how Im going to do that yet :P