Make the diagram big enough that all the important information can be included in it, and can be interpreted easily by a reader. A diagram should not be ornate. Use simple, clean lines. By labeling al1 distances, charges, and forces in a diagram, you bring together in one place a great deal of information that is scattered throughout the problem. Once it is recorded on your diagram you do not have to search for it again.
Labels help to prevent serious errors.
Carefully labeled diagrams significantly reduce the number of errors made in problem solutions. A cluttered diagram is hard to interpret. For clarity, include only relevant information. For example, show only excess charges, but do distinguish between charge on a surface and charge inside an object. Do distinguish between free and bound charges - do not make your drawings of polarized molecules in an insulator look the same as a drawing of a polarized metal.