[header] How to decorate difficult bedrooms [title] Decide on a colour theme. [step] This may be a subtle theme or the entire base of your room. Most room decorating articles say this, but it is quite important, otherwise your room will look random and untidy. 
If your walls are non-paint-able you may wish to add a large, coloured pin-board to your room. If you're lucky, your room came with one of these, but they are relatively easy to make and a savior when it comes to colour themes.