Cabinet /Cubby design?

So I have some very basic cabinets inside my TD.

They are about 20 inches deep. I've been using them as is ( nothing inside just a door) for a few year now. I pretty much have to pull everything out to rummage through it all to find a towel, or the T shirt I want or my toothbrush. Any tips or suggestions to make it easier to use? I'm thinking about adding a shelf at the top where I could put my towel and bathing stuff, or should it be on the bottom?
Thanks for the ideas
Tom
They are about 20 inches deep. I've been using them as is ( nothing inside just a door) for a few year now. I pretty much have to pull everything out to rummage through it all to find a towel, or the T shirt I want or my toothbrush. Any tips or suggestions to make it easier to use? I'm thinking about adding a shelf at the top where I could put my towel and bathing stuff, or should it be on the bottom?
Thanks for the ideas
Tom