In a small space consider painting everyroom and all hallways the same neutral colour. it makes the home feel larger because the space flows from room to room.
Also try putting framed prints on top of each other, tricking the eye that the walls are much higher then they really are.
When hanging curtains, put the valance or topper to the ceiling and hang the curtains right to the floor. this gives the illusion of larger windows and a larger space.