How do you organize stamps?

I have recently found a box of stamps being thrown out of an old rental property left behind. See the ungodly amout of flags Roosevelt and Lincolns I thought them to be fakes. But i kept them anyway. Ive decided they are real and ive got a new very old collection of stamps. Researching them for the $ I could make, ive decided I'm gonna start collecting them and just sale the duplicates. But this collection was in shambles. Mice had eaten parts of letters. I saved everything anyway. Any advice? I can't afford a hobby as I'm barley able to support wife and kids as is. How should I figure out whats what. Ive