How can I organize a tiny closet?

Pam: maybe this will help. Why not put a curtain rod with curtains over it... to keep some dust out? (You can get curtains very cheaply at Marshalls or Home Goods.)

https://www.housebeautiful.com/lifestyle/organizing-tips/g2376/storage-tricks-small-closet/

If you want more room for hanging things you can move one rod up higher and add another rod about half way down taking into account the length of things you want to hang. You could do one closet that way. You could move up the rod in the second closet and then add more shelving to the bottom. AS far as doors you could add sliding barn type doors if you have wall space to do so or you could use a tension rod in the doorway opening with curtain panels.

You could put a tension rod and hang a curtain or a pretty shower curtain to keep dust out.

Also there are clips to attach to the hangers to layer clothes...these can be as simple as tabs from cans, just put the hanger top through the hole of the can tab.

the closet in my room in our old house is 92 inches wide and 28" deep. It orig had a shelf all the width of the space and on either side a front to back rod. That meant most of the interior of the closet was unused. We put a shelf under the long shelf (allowing a lot of room for stacking sweaters, etc) and then hung a rod from that shelf. We more than doubled our closet space. We could help a lot more with more information about the exact size and shape of your space.

https://www.apartmenttherapy.com/small-closet-organizing-ideas-207307

I would definitely hang a curtain over the clothes if you can't fit a door. Tension rods are ok, but will fall if you pull on them too much. If you can get a cheap shower curtain bar, cut it to size and mount it in the doorway and it will be much sturdier.

I've made over many small closets, here is what I usually do.... 1) move that shelf up to accomodate plastic cubes for storing out of season clothing; 2) move the top rod up under the shelf, 3) then add a second rod below for pants folded over the hanger by adding a 3"x 4" piece of lumber on each side of the closet, and then mount the small hangers to add another rod. 4) you can add another shelf on top of that lower rod for shoes.

As to covering the open closet, you could add drapes, or add a blind, or buy a used door at Habitat for Humanity Restore. Also don't forget under your bed for extra storage using old drawers by adding mini wheels and a handle to them.