1. Bed risers are you friend.
2. Keep things like power cords off the floor by using drywall hooks.
3. Giant storage containers can also be used as tables.
4. A storage ottoman is a versatile way to create more space.
5. A rug can really bring your place together in a cozy way.
6. And plants can help make your room pop!
7. A coffee table works as a cheaper alternative to an entertainment center.
8. Decorate by the 10%, 30%, 60% rule.
9. Fairy lights help change up the harsh fluorescent dorm lighting.
10. Tapestries are another cheap way to add color and decoration.
11. Get a matching soap dispenser and toothbrush holder.
12. A toolkit is a dorm room MUST-have.
13. Hack your AC using a wet washrag.
14. Laminate charts so you can study in the shower.
15. Use string and clothes pins to hang your photos without nailing a frame into the wall.
H/T to these threads by fatrice_, numa_numa, and brienoconan.
Some comments have been edited for length/clarity.