Clear the room to get started and work out what you will keep from your 'old' bedroom and what you will happily throw out. Next hunt down some white paint that has a bluish tint and this will help to create a relaxing and soothing environment.
The next step is to consider your flooring options. If it's neutral already - leave it that way. If not, dark brown (walnut) stained floorboards will look both stylish and bring a touch of warmth to the room. Rugs are also essential in the quest to add layers of texture and warmth. Choose sheepskin rugs as these will bring creamy tones as well as a splash of luxury.
On to your furniture - walnut works really well with the white and the grain in the wood will add a textured feel. If your wardrobes are currently of the free standing kind, it might be time for a re-think. Fitted sliding wardrobes are a brilliant way of transforming not only the overall look but the amount of space in a room. With many styles to choose from it won't be hard to find something that works with your neutral theme. Sliding mirror doors or dark wooden doors will both work with the scheme. With that 'made to measure' element, there will be no wasted space and masses of additional storage in your room, enabling you to dispose of all those old furniture pieces that have just felt cluttered.
The curtains need to be on the full side with perhaps taupe or cream as the colour. If you are able to make them yourself then why not buy a little extra fabric and make a bed runner and some cushions covers to match?
If your bed is dark brown, a white/cream/taupe duvet cover will sit very well in the scheme. Add some cream throws and this will contribute more neutrals and textures.
Last but not least, you need to accessorise. If you have managed to revamp some of your old furniture and saved some money in the process, why not have some fun splashing out on a few hip accessories. Vases and dark brown wicker baskets will complement the neutral look. A few prints for the wall with those selected tones still in mind and you will have created a modern masterpiece using just neutral colours.