A few years ago, I wrote a book about realistic crayon drawings. What a joy it was to create, for I had brought my childhood dream into my adult professional life. I wanted to share it with others, for few knew that crayons are actually a wonderful fine art medium. They're not just for kids!
Use Crayola. These are the best and have the best color saturation. Use a paper that will grip the color evenly. I like Stonehenge or illustration board. Have a good hand_held sharpener handy. Always try to keep a point on the crayon. This makes it go on more evenly. Apply the crayon in a professional manner. Just like you would any other fine art tool, use control and be deliberate. Don't become five years old again!