This tip is kind of in two parts and the title says it all. However, many people have a lot of clutter in their home or office space because they simple don't make a habit of putting things away. They tell themselves they will set aside some time later to "catch up" and the longer before that day comes, the more stuff stacks up and then the bigger the job becomes and consequently the chances of getting it done are greatly diminished. I am a big fan of "put things away as you go", but if that is outside your realm of thinking, then at least put things away once a week. Designate the best time to do that and create an appointment for yourself that never gets violated.
The next part of the equation is to make sure that when you put things away, that the next time you need that item, it will be ready to use. If your files need to be updated before putting them away, then do it immediately and then put them away. If you need to repair an item, do it before putting it away. There is nothing worse than pulling out something that needs repair or that is useless to you when you need it.
If you are trying to eliminate the stress of clutter in your life, implementing this one tip will rock your world, I guarantee it!