Organize in little windows of time.

What you need:

Clean out a kitchen cabinet
Open mail and shred or recycle what you don’t need
Photograph and recycle any bits of paper you’re keeping for reference like business cards or a flyer
Organize by category of belongings like putting all your batteries in one container, travel adapters in another, etc.

Go through one category of clothing in your closet and donate unnecessary duplicates or things that don’t fit
Go through your bathroom cabinets and discard anything that’s expired or you haven’t used in the past 6 months
Corral all your cleaning supplies in one place

Organize your bookshelf and make sure you’re not holding on to anything you’re never going to read
Go through all your hanging clothes, collect duplicates and the items that don’t fit, and drop them off to be donated
Follow the exercise in the next step to organize your junk drawer and figure out where items that tend to cause clutter really belong