There are three parts to this personal organization system.
Part 1: A place for everything, and everything in its place.
Take that literally. One by one, find places for the things you use. Let it build at your own comfortable pace.
Pick a place where it is easily accessible, and won’t be moved or in the way. Put your keys on a hook near the door, not on a table where things always get moved around.
A right spot is recognizable by the small feeling of relief you get from having one less thing to worry about.