You can have two small apartments of the same size and same layout, with the same furniture inside both, and one apartment will look and feel larger than the other. It's all about arrangement. When working with a limited space, arranging your belongings along the walls will open up the center of a small room. When the center of a room is broken up, you get a cluttered look, that gives a feeling of confinement.
Windows
If your small apartment has large windows, use them to your advantage! Let as much sunlight shine in as possible. If you are concerned about privacy, use sheer curtains made of fabrics that obscure the interior of your space, but still manage to infuse your rooms with light.
Painting
Here's a painting tip that will help you to make the best of your small space: The application of a light color to your walls will make your room seem larger than it truly is. If your ceilings seem too low, paint them a color lighter than the walls. This will make the ceiling seem higher. If you paint the walls a lighter color than the ceiling, the room itself will seem larger.
Mirrors
You can also convey the illusion of space with mirrors. The effect is subtle, but you'll find that mirrors are functional in more than one way. They work well in narrow hallways, and hung on the narrowest walls of rectangular rooms.