How can I organize clothes in a small room?

What have you got to work with? Any dressers, highboys or similar? Closet space?

You can try using a rolling garment rack from Amazon. You can even buy a covered one.

First get rid of what you don't wear or fit you right anymore. These helped with closet space in my grandson's dorm.

https://www.amazon.com/gp/product/B01254CB0K/ref=ppx_yo_dt_b_asin_title_o04_s02?ie=UTF8&psc=1

PUrchasing these things from Target or Walmart or such, stack two of those "knock-down" shelving units that look like two [2' vertical squares hooked together] on top of each other, and secure to the wall. Place another on the floor, horizontally, to the right of this. Now repeat the first colomn you created on the right side, also securing to the wall. Connect the two columns at the top with a coordinating (in color) closet rod. You can keep folded jeans, sweaters, etc. in the columns on one side; underwear and socks, etc. in baskets in the column on the other side; and shoes, etc. across the bottom. You could even connect a shelf above the closet rod at the top for more storage.

These units come in white, black, and brown to match your needs. You can always run a curtain across the whole thing to hide the clothes if you prefer.

This is what I. did for my daughters shared bedroom and it was a HUGE Spacesaver! https://www.thatsweettealife.com/diy-storage-bed