Tips for managing the files and folders in a mismanaged laptop

I am pretty messed up with my laptop. I used to play games and watch movies most of the times on it. So I place most of the files carelessly here and there on the hard disk and concentrate on my game and movies. Later, when I need those files, I have to work very hard to retain the locations of those files. Can you please give me some tips to manage the files on my Laptop? Please provide me some tips so as to maintain my laptop storage properly. Also tell me how much space I should allot to C drive and how much space to my movies and games drive.
