1. Start with the easy stuff. Eliminate anything that's broken, damaged, or no longer wanted. Then go to out-of-the-way places like attics, crawlspaces, and garages. Making progress in 'easier' areas will build momentum to go through the harder-to-decide areas.
2. Ask Yourself, "If this disappeared tomorrow, would I run out and replace it? If you wouldn't miss it or need to replace it, it's probably not worth keeping.
3. Don't be a storage unit for others. If friends or relatives have left things for you to store, it's time to ask them to pick them up-or arrange to have them shipped. You may need to be tough and set a firm deadline, after which you will donate the items.
4. Ask for help. Although you can do much of this work on your own, a family member, a good friend, or even a professional organizer can help make the job more manageable.
5. Decide what's really important. Pretend you are moving overseas, and the number of items you can take will be severely limited and it will cost a small fortune to ship things. What items belong on your list? These are the things that matter most to you!
6. Is this something from a lifestyle I no longer have or want? For example, if you have three cabinets full of plastic containers, but only cook for one or two people, you probably can lose a few plastic sets--and dishes, pots and pans, etc.
7. Schedule a regular time each week--or several days per week--to work on rightsizing. Realize that rightsizing is a life-changing project, not a sprint. You didn't accumulate everything overnight, and you won't sort it all out overnight either.
8. Value what you keep. The fewer things you keep, the more you will treasure and enjoy what you have, instead of tucking them away in a closet or stacked among dozens of other things. These are the few, meaningful items worth having in your personal space.
9. Prevent new collections from forming. Instead of material gifts, ask people to spoil you by sharing time, enjoying new experiences and indulging in luxuries (spa certificates, imported chocolate, a musical or other theatre production, gift certificates for dinner out, etc.) -- the things you love and want but don't always buy for yourself.
10. Use age to your advantage. Now is a great time to "gift" items you will eventually want you family members to have. Take a photo (preferable a digital one) of them holding the special item and create a digital scrapbook of "next generation" memories... making your special people happy and freeing yourself of extra "stuff" that you have been charged with keeping for posterity.