Where do you start?

When you see a room like this...it is easy to not do anything because you just don't know where or how to start.
You have to take a tiny piece and just start there. You can't think.."I have to clear this whole room", you can start by saying, "I want to clear off this chair so I can sit down." Then you need to start the sorting process.
You have to make decisions, and you need to make them fast. If you spend 10 minutes trying to decide if you want to keep the smelly old backpack that your daughter used in kindergarten (she is now in college)..because you remember buying that backpack and you remember her first day of school and how she was scared, and you remember walking her there and how nice her teacher was and.....and....and..... You get the point. You need to pick it up and try not to apply the memories to that piece. You STILL have the memories, no one is going to take them from you. But keeping a backpack that is falling apart and smells because at one point in its long life it was left out in the rain and then got thrown in the garage...isn't going to help you remember that day any better. You can take a picture of the backpack if that would help you to let it go. But you need to take seconds to decide. That helps you to take the memories out of the picture(at least a little bit).
But you just take one thing at a time and make a decision. Does this belong in another room? (If it does, put it in a box or bin that goes elsewhere. Don't physically walk it to another room because you will get distracted. STAY IN YOUR TARGET ZONE!!! (That is the chair you are working to clear)
Do I need to keep this? - Do I love it? I can't live without it.
Can someone else use this more than I can? Will it enrich someone else's life?
Is it something that should be stored? (Christmas, Halloween decorations)
Is it something that can be thrown away? Broken items, missing pieces, worn out.

Don't overwhelm yourself. Start small. Clear just that chair. Then if you have the time and energy (many times seeing some improvement can help to "jump start" your organizing engine.)
Don't try to bite off more than you can chew....remember what your mom told you, "Take small bites so you don't choke."