I sometimes advise clients to do a "virtual move."  While decluttering, imagine that you are moving.  Would you get rid of this or that if indeed you were moving?  If so, get rid of it now.  If someone else can use it, offer it to a friend that may need it, or give it to a charity (and get a receipt for tax purposes!)  Keeping something that you wouldn't want if you were moving makes no sense to keep now.  Look around and see what else you would not pack.  You might be amazed!  
Working with cleaning up and organizing paper can sometimes be the toughest job.  It is for me.  Figuring out what we need and where to put it, what we can get rid of and what to shred...it is nearly enough to make me scream at times. 

I have gotten rid of nearly all my instructions booklets that come with appliances.  I found I could get them online if it was needed.  I keep receipts after checking them off on my credit card bill only if it is something I might return.  Grocery, restaurants, hotel stays and pest control services, I can obviously get rid of.  Anything with personal information or credit card numbers gets shredded.  I then use the shredded paper as packing material when I send something in the mail that might otherwise get broken.  

If I am not sure if I should get rid of something, I ask myself how tough it would be to replace it.  If it is something I could get online, like last month's bank statement, ditch it.  Out of date maps and travel info gets ditched.   Work through your pile and get rid of as much as you can.  That way when it gets put away in files, you will know where to access it ...and it may be one of several in a file rather than one among hundreds!!!
I love author Gretchen Rubin's One Minute Rule.  She says "...perform any task that can be completed in less than one minute, without delay. "  OK, so you see dishes in the bedroom that should be in the dishwasher in the kitchen.  That is easy and you can do it in one minute.  So rather than making a mental note to do so later...do it now.  You notice your sweater is not hung up--do it now.  You see that the letter from the health insurance company is still sitting on the dining room table.  File it away...now.  All these things are examples, but I think you get the point.  Don't delay.  Do it in just a minute and it makes a world of difference on keeping things organized.  
Are your shoes all over the house and never where you need them?  We have a "no shoes household" so we keep our shoes in a shoe organizer right at the door where we exit to the garage.  Slippers are there too, so I can put those on to keep my feet warm inside.  I never spend time that way running around and looking for my shoes.  If you don't take off shoes in your house, just keep your organizer by wherever you dress each day.  A lot of wasted time can be replaced by calm if you keep your shoes where you expect them to be!
Feel like  you are sometimes drowning in video games?  Now is the time to purge through your games, and make money getting rid of the ones you no longer want.  Go to http://www.decluttr.com and sell the ones you don't play anymore and reclaim that extra space.  They even have an app for Android or iPhones, so there is no excuse.  Don't just trade them in for more games to take up space.  Get the cash so you can shop around for something you planned to buy anyway.  You'll get top dollar doing this sooner rather than later, as the value goes down with time and newer and newer games are introduced.  They even pay shipping!  Just like my post about getting rid of textbooks and selling them online, it is a win-win.  More closet space and money in your pocket!  And who couldn't use more of both!
Office supplies might be all over in your house if you are like many of us.  Consolidate all those and keep together in your office location within your home.  Test any pens and markers, ditching any that no longer work.  Keep sticky notes together, and use a compartmentalized drawer within your desk to organize.  Put extras you have on hand on a closet shelf in the same general area.  Before getting any new office supplies, check your back ups and be sure you don't already have it!  You'll save money and be able to find what you need.
Once you have done some serious purging, you may have a lot set aside for a yard sale.  Planning properly is a big key in a successful event.  I like the following guidelines which I read about in Real Simple Magazine:

2 weeks before:  Gather all the items you intend to sell.  Take a walk through the house, room by room, to see if there is anything you may have missed and add it to the pile.

1 week before:  Get stuff "sale ready" by cleaning items and making them appear that they came from a well cared for home and are therefore going to look more tempting to the buyers.    Organize items by category, such as KITCHEN, CLOTHES, TOYS, ENTERTAINMENT, etc.  Get plenty of paper or grocery store plastic type bags ready to have available to buyers.  Have bubble wrap on hand for anything breakable!

A couple days ahead:  List on Craigslist, including several of the most sought after items so people are enticed.  Hang signs in the neighborhood.  Advertise in local paper.  Send an email to your friends and ask them to spread the word.  Do you have a community website where you can post?  If so, that is a place to post!   Purchase poster boards for signs to note Half Price or All items $1.00 when the end of the sale is approaching and you want to get stuff moved.  Go to the bank and get SMALL BILLS.  Get at least $100 in smaller bills--4 $10, 5 $5, 25 $1 and $10 of quarters.  You don't want to lose ANY sales at all, and surely none that are because of not having the right change.  

The morning of:  Set up the items, attractively displayed, and set your cash station.  (Be sure to have the cash station in your sight at all times, or the siight of one of your helpers).  Allow plenty of time for set up.  Offering free lemonade is a nice touch and be sure to have pleasant background music that would have a broad range of appeal--Sinatra or Classical are both good.  Wear an outfit with POCKETS to stash exact change sales so you don't have to take time running over to the cash station each time.  As you get closer to the the end of the sale and you see traffic lightening, consider posting a sign saying HALF OFF or EVERYTHING ON THIS TABLE $1.00.  Make signs up that morning ahead of the start of the sale so you have them ready to go.  Stash them safely inside the house so they don't get mixed into things and cause confusion with buyers.  Have a bottle of water and a back up bottle ready for yourself so you don't need to run inside when you get thirsty.  

At the end of the sale:  Pack up leftover goods in boxes and/or bags for charity pick up.

After the sale:  Congratulate yourself on a job well done.  Your purging has produced some extra money and your no longer needed items are now in homes where they can be used and enjoyed.
This question is asked of Professional Organizer very frequently.  What do you do when the kids leave and their stuff is now cluttering your valuable storage space?

Call each of the children and explain the situation that in the past it was no problem to store their things, but you are now organzing and have need for the space.  Could you please get those moved to your place in the next two months?  That is a reasonable timeframe and you are delivering the message in a gentle manner.  You might get even prompter action if you state that you are using the space to make a guest room, or you now will be storing the bikes and the patio furniture inside for the winter.  Also, let them know that you will be happy to donate any of the items they don’t want, or even add them to your trash if they are not of use to anyone.  If the kids are out of town, offer to ship items they wish to keep.  Go over with them by phone what you believe is theirs so you aren’t shipping something they are just going to give away or trash when it arrives!  You can even email photos if there is something they don’t remember.  If all this fails, let them know you are clearing out their stuff into a storage unit, and they can either get it from there, or they can pay the rent on the unit after the two month period is over.  Set a deadline—that is important. 

Stuffed animals can be put up in a net in a corner at the ceiling level where you can still enjoy looking at them, but they don't get in the way.  Children sometimes choose the corner where they can easily see them when lying in the bed so they can say good-night to them.  Every so often, be sure to get up there and dust them off or vacuum them to be sure they don't simply collect dust!
For me, losing my keys used to be a huge frustration, and frankly happened way too often.  Now I have hooks on the wall, right where I enter the house from the garage and the first thing I do is hang up the key.  This prevents the issue of lost keys, and adds calm to my life!  Once you get your hooks up, get in the habit and you will have one less thing to worry about!  And, isn't that what it is all about?