The secret to any developing interior design is balance. Decorating a small room so you open a little space and make it look bigger is possible if you maintain a number of design strategies in mind. In a truly compact place to live, you must use every inch of space available including your wall.
Apartment decorating ideas usually do not consist of paintings and Hanging Walls, but because you are in a rental does not mean that the painting comes entirely from the question. It might invite to hang a mirror to cover a blank wall space, but make sure it reflects something worth seeing.