Judith Dold, a professional organizer from Twilight Organizing, gave four easy-to-remember steps to SHARP members who were overwhelmed by the possessions they have accumulated: STOP
 
SORT one category at a time.  Go through the t-shirts, or the books, or one closet.

TOSS articles you no longer have a reason to hold on to.  Don’t keep just because it was expensive, or you might need it later.

ORGANIZE the things you keep and always return them to their “address" or place.

PERSEVERE and resist backsliding.  Start small but keep at it.