I'm trying to keep my linux installation as clean and as neet as possiable. Every other time i have used linux i always have all my downloads and stuff scattered in my home dirs, between my root and my general use user account. I am looking for suggesions on how to keep my files orderly, where should i put all my files that all users on my system are able to access. Like music. or where should i put all the packages i'm about to install, and do i always have to log onto root to do the install, via su command? Should i create a user named mp3.... etc to store my mp3s and one called pictures to store pictures... etc... can someone plz give me some suggesions?

What I do is keep a directory called /pub where I stash all sorts of stuff. Downloaded files, program source for stuff I'm compiling, etc. If you have multiple users, you can make it readable/writable by all users (or just certain groups). Works for my purposes anyway.

You can install software as a normal user if you want, but typically it means that only that user will be able to run the program. For a system-wide install, you usually have to be root.

one more question.... how should i setup the permissions for this directory. Considering i want only my users to use it and none else..??

You could make the directory owned by root, and in group 'users'. Put all your users in group 'users' also, and give them read/write permission to the directory (chmod g+rw).