Cool it Down
Nothing is worse than waking up covered in sweat. Something as simple as a small fan running can cool you and your room down significantly. Studies show cooler rooms are much more conducive to sleep.
Try to keep your bedroom as focused on sleep as possible. The more papers, electronics, and clutter you have lying about the more chaotic and claustrophobic a room can feel. This will also lead to fewer distractions while you are trying to sleep.
Bedrooms, specifically small ones, can have poor air flow and feel stuffy. Opening a window will help get more air circulating and at certain times of the year cool your room better than a fan.
The mattress is the work horse in your bedroom. While it may not be the most glamorous piece of furniture it takes on the entire work load while you sleep. Make sure to clean it regularly and replace it if it is worn out. Remember you should ideally be spending six to eight hours a night on your mattress so keeping it in good condition will make all the difference.