So here is my brief and over simplified way of organizing.
1. Decide what you want your space to be.  Is it a linen closet, coat closet, etc?  This cabinet had everything from dishes to fabric.  
2. De-junk.  One of the greatest things I've ever learned is, "You cant organize clutter"  so get rid of it!  I do this by pulling things out one at a time making piles.  Keep.  Give Away. Trash.  
If the thought of doing it all is to overwhelming do it in stages.  Like in this cabinets case, I did one shelf at a time over the course of a few days.  
3. After putting away your piles to their various locations it time to put back what you do want in your space, organized!  I needed this cabinet to be my craft space.  So only craft/sewing supplies are welcome here.  
 I love my new craft space, it is so easy to find what I need and so easy to clean up when I'm done!
 
 

