In which case you can play around and find out precisely what you like at your leisure and not vex about whether the furnishings you bought would suit. But a flock of people won't be able to do that and they will need to fall back to doing it the old fashioned way, or of course you have another option, and that's to recourse to the use of home decorating software. Software puts most of the visualization into perspective, especially with bedroom design. 

The best way to start is to get a pencil and a piece of paper and to mark out very close to what your room shape is. If you have trouble visualizing it then move into the bedroom and see what results you get. Next you should mark out the most visible aspects of the existing bedroom design which will be unchangeable, like doors and windows. Remember, stay objective and just pencil in what is currently existing and not what your mind might be seeing.

Then ideally you should settle down on a color scheme. It doesn't need to be the same as the one in your existing bedroom design, it might be nice if you can change the whole thing round and turn the whole room on its head. After you settle on a color scheme there is only way to go and that is forward.