S.G.
S., I have been an interior decorator for many years and to be honest, organization is half of my battle for most of my jobs. Although I stopped practicing a year ago, I still give advice from time to time.
The frist thing you do is pick on place to start. For some people it is the dining room table that ends up being a catch all, or maybe a bedroom. Just pick one place. When you have finished go on to the next place.
Inform the family that this something that you have to do. You are going to organize one place at a time and it is going to stay that way.
Begin with a laundry basket, 2 or 3 if you have to. Go through that area and remove everything that you dont want to keep or is out of place. Put it in the basket. Once the room has been gone through. Vacuum and dust the room. What is left should have a place, if it doesnt, remove it.
Take the baskets to a central location. You may choose the living room to work in or maybe another room. Go through them thoroughly. Make a pile of things that are going to be kept and things that are not. Get rid of things immeidately, dont let them lie around. When you are finished the items that are left, should be the items that you would like to keep but have no home. If they belong in that room but have no place, begin at that time to think about storage for those items. The type of storage will vary depending on the items that are left. Once that room is complete you should have a basket with a few things you wanted to keep but found no place in that room.
Take those items and put them aside, finding a place for them is not your goal. Start in another area. Do the same thing. You may find that some of the items from the previous room find a home in this area, if so, that is great if not, continue on.
When you gone through your home entirely. Each room will have only items that belong within it, and each item will have a home. You will then have a basket of items that you wanted to keep but have no home. Go through the basket item by item and find a place for it, if there is no place for it, store it in the basement or give it away.
By eliminating clutter, you eliminate much of your need for organization. You will find that keeping your home organized will be easier. During this process, you will need to check each area you have organized and hold you and your family responsible for items that are left out, or removed and never put back. Good Luck!!