If you are painting a wooden kids chair, the word to keep in mind is "durable". A child will use their chair to sit on, stand on, throw, build things on, and take outside. The uses are limited only to the child's imagination.
Step One: Preparing the Wood
Prepare the raw wood by sanding it down well all over to remove any oily fingerprints, scratches or other dirt on the raw wood. After you have done this, cover the chair well with a coat of good oil based primer. This will allow the paint to grip into the wood and hold better through all of the rough wear.
Step Two: Applying Paint
After the primer has dried per manufacturers instructions, apply a coat of good latex enamel. When purchasing your paint, be sure to let the paint dealer know you are using it on children's furniture to enable you to buy the safest product for your child. After the first coat dries, rub gently with steel wool and wipe off the dust. Apply another coat of paint for a smooth finish.
When the paint is dried, you can apply decals or add other colors of paint for trim, such as the child's name, dots, animals or other graphics.