Please Help My Mom Get Her Basement Organized!

The last time I went home to Virginia, my mom invited me to join her in the basement.

  She led me to a corner that had a ton of decorative flowerpots, home decor items, and party serving dishes.  Then she said to me,"Take a look if you want anything...I don't need all this stuff. I don't have any more room in the house for it."

Let's back up. In many ways, I am very similar to my mother.  My mom is really organized - see an example of her closet on the right that she and my stepfather designed and built.  They combed through magazines to find the perfect combination, then he built it from scratch in his workshop.  She selected neat organizers that matched from Tuesday morning.  Overall, it is quite impressive.

The Basement Problem

However, while I am a "purger" and like to get rid of anything in my home I don't actively use (except all my art supplies!!), my mom is more of a "keeper".  Her basement has become a collection place for so many items from their combined households when they got married.  The issue is that they don't have room in the house to put the decorations, extra chairs, etc. anymore - see below:

The decor area:

The graveyard of rocking chairs and dining room chairs from combined households:

The overflow area for household supplies that she does not use everyday (this needs to stay in the basement but I want to organize it better for them):

My mom is feeling a bit stressed from the clutter in the basement.  She feels guilty that she bought some things for use in the house, but ran out of room.  Many of the decorative items are not returnable.

I am thinking a yard sale might be best to sell a lot of the things they don't need, and then they could do something fun and spontaneous with the money.  That could allow her to feel like the purchases were not a waste.

Progress Thus Far:

I mailed her some tags that I bought at Target to start tagging things that she knows she doesn't need, things she wants to keep, and things she is not sure about. When I go home over Thanksgiving, we are going to go through it all together.   I will likely return in the Spring to help them have the yard sale.

Help me!

I would love your help.  Do you think the process is right so far?   Any tips or pointers for the process, or do you have any advice on having a yard sale?  This is my first time, so welcome your expert input!  I look forward to keeping you updated on the progress!