Painting the room in light colours is a great way to create a larger impression of room. However, don't rush for the tin of white paint, there are many other great colours that will work well. Creams and neutrals often work better than white and lift the room also. Use soft wool carpet, and small subtle patterned bed linen to aid this room's size.
A small room is not the place for a four poster bed, so use a low set bed with some drawers below it, as well as room for some blankets and sheets. Concealed bases make a bed look like it's floating and also conceal clutter. Bunk beds are also perfect if it's a child's room as they take up half the space, and can bed two comfortably.
Using the walls of a small room is the perfect way to create the impression it is larger than it actually is. If you clutter up the room with suit cases and knick knacks everywhere, then it's going to look small. Book shelves and drawer organisers are great, as are shoe storage racks inside wardrobes. In small bedrooms, everything has to be in the right place - so get organised with storage to achieve this feeling.
Pale furniture creates a roomy feel as do tall pieces of furniture, over wide ones. Make sure what you choose is simple and not fussy and perhaps even a little minimalist. Furniture with mirrors is also a good way to create the impression of space through the utilisation of reflection and light.