Step 2: prepare for painting
Frosting the jar helps diffuse the light and gives a nice glow to the entire jar, but I found it unnecessarily time-consuming to take apart the jar and frost the outside.
For much less time, you can make a newspaper mask and spray the inside of the jar instead. As an added benefit, you will not have to worry about paint scratching or flaking as it is moved around.
Place a quarter sheet of newspaper snugly over the mouth of the jar to create an impression and cut around the inside of the mouth using a utility knife.
Once your hole is cut, attach the newspaper with painter's or masking tape.
Place your jar (or jars) in a shady location for painting.