No matter what it is you're organizing, you first need to clear a workspace. Even if that means pushing other things into another pile, you'll need the room to sort.
Pick an area and get started. That could be a corner of the room, a shelf in the closet, a desk drawer or a 12" square spot on the floor; there is no 'right' place to start, just make a decision and move forward!
Bring a group of items to your work space and sort them into categories. Empty laundry baskets or cardboard boxes work great for sorting, be sure to label each box with a category and keep sorting items until the closet/shelf/corner is empty. Move on to the next spot and keep going. As your sorting, make sure to have a place to put trash and items to be donated.*
When you're done sorting and purging it's time to put away what you're keeping. Have you thought about how you want to use the space/closet/surface? Put items that are rarely used way up top, or way down below, or way in the back. Frequently used items should be stored where they are used and you shouldn't have to move more than 1 item out of the way to retrieve them.
Remember that things should be stored in a place that makes sense to YOU.
*Take items to be donated now! Get them out of the house, make it a priority.
