Decorating any room is always the fun part, but you don't want to go overboard with tchotchkes in your meditation room. You should only surround yourself with beautiful and meaningful items, not a bunch of clutter that will ultimately distract from why you're there.
Meditation rooms should always be painted with light and relaxing colors. Greens and blues are great choices, but you wouldn't want to use red or orange -- these colors are too stimulating and provocative.
Candles provide great ambience, and so does natural light. Objects of higher authority are common finds in meditation rooms to help bring feelings of peace. These can be in the forms of statues or photos -- whatever evokes a positive and grounded feeling. And you may also want to include a dream board that you've created. This is a large piece of paper or poster board filled with images that remind you of your goals and deepest desires. It's believed that if you meditate on these things and envision them in your life, they will come to you.