The first thing when designing a room for boys is to ask the things he likes. If the boy likes to draw your favourite cartoon, you can decorate the walls with images of favourite cartoon super hero cartoons for example, or even a view of the forest, if there are no figures, selected favourites. You can enter a room with a favourite character to give kids room wall decals.
But keep in mind, as the growth and development of the child, of course, things like going to continue to change, to choose a design that is not too childish so that when they grow up, you do not need to change the decor of the rooms thoroughly. Not only decorating the walls, you can choose a bed cover with a particular theme that matched the overall decor ranging from walls and floors.