Most students are not allowed to paint their walls, but there are numerous ways to make a room exciting without the use of paint. If you want to go for a whole wall color minus the paint, you can put fabric on walls with liquid fabric starch for a unique look - this can be removed easily and reused. Another way to attach fabric to the wall is to use tacks or tension rods
A rug will define your space, make the room homier and cover up dingy old carpets in res rooms and rented apartments
Use multi-purpose furniture. A small table or stool can function as a bedside table, guest seating, night stand, etc
Make the space your own, attach posters/pictures with removable mounting squares or safe release double sided tape.
Take advantage of limited floor space with tall, narrow bookcases and drawer units. Use shelving to maximize vertical space. If the budget allows, splurge on stainless steel for a reflective surface that will make your space look bigger.