There are many elements which make up a Montessori bedroom. Here are my five tips if you are planning from the start or wanting to make changes to an existing room. 

Tip 1. Consider your family situation, your home and what will actually work for you. For our family it means having our two children share a bedroom. What room will work for you (upstairs/downstairs/near your room)?

Tip 2. Consider the listed elements individually and how they apply to you.

    Beauty

• What decor do you consider beautiful (colours, fixtures, textures, floor rugs, bed covers, artwork, furniture)?
• Is the room calm, is it aesthetically pleasing?

    Order and Independence

• How can you instill a sense or order and independence (think storage and display options for toys, books, clothing, personal care items - for younger children consider freedom of movement).
• Can toys, materials and personal items be easily reached by the child? Can the child reach the light switches?
• Is the room uncluttered? It is easy for the child to see where everything is kept and where items belong?
• Consider low hooks (for towels, robes, backpacks, jackets), shelving (for books and toys), low drawers/hangers/baskets (for clothing).

    Comfort

• Montessori would steer us towards natural fibres and materials (cotton, wool).
• Does the room have suitable temperature control? Is the room suitably warm (consider blankets, floor rugs, draft stoppers).
• Does the room receive natural light, can the room be darkened (for daytime naps)?

    Safety

Safety is so important as the idea is the child (whatever their age - from birth) can be left alone to sleep and play independently in their room. 

• Are all the toys/materials in the room age appropriate (no small pieces, no pull apart pieces). If not leave these types of toys out of reach. 
• Do you need a door gate or other safety provisions? Are there any dangers in the room (heating appliances, power points, unstable furniture/shelving)?

Tip 3. Look at examples for inspiration. Setting up a bedroom by reading about Montessori is so, so difficult. You need to see real life examples. Keep in mind that no one room is perfect and everyone has their own reality of a Montessori environment. Every family and every child is different so what works for one family might not work for the next. 

Tip 4. Consider and follow your child. Think about your child's tastes and needs especially as their personality and likes become more obvious. It's a good idea to discuss ideas with them (depending on their age) and allow them to lead the decorating/arrangement/changes as much as possible. I personally like to display children's artwork and photographs. I have my older child choose his own artwork, bedding and furnishings. 

Tip 5. Lie, sit, crawl around the room. Try to see things from the child's perspective. What can you see, what can you reach? How does it look? Re-assess the elements from tip 2 from the child's perspective. 

Pictures say so much more than words. There are many examples of bedrooms under the Australian Montessori Families and International Montessori Families sections. You can read about Caspar's room (as a four year old) here. Below is a wonderful illustration from Michael Olaf's The Joyful Child.

Montessori infant rooms need particular care and attention. You can read about Otis's room as an infant here. 

My final suggestion is to take it easy. Changes can be made gradually. Also there is no need to incorporate all of these ideas and concepts - I've never seen a perfect Montessori room, take what works for you.