If a wig is required, discuss it with the best wig-maker that you can find. Should you be able to draw supply him with a rough sketch. Failing this you will probably be able to find an illustration or an engraving which, though it may not be exactly what you want, will help you to explain your idea.
I have made a large collection of different engravings of interesting types, and the work of the old caricaturists I have found very suggestive.
Visit the wig-maker two or three times before the wig is completed, it will then be made under your direct supervision and will probably be more successful in every way.
Remember that the character of a face depends on three elemental qualities, form, colour and expression. The first two are almost constant, the third is susceptible to perpetual change.
The grave, the gay, the ascetic, the debauched, the æsthetic, the philistine, the spiritual and the material, each will have his distinguishing colour and form. The expression will depend much on the various moods portrayed during the action of the play.
Make the characterisation as definite as possible, for the size of the stage demands a certain breadth of treatment. Do not forget the distant patron of the pit and gallery, for though his monetary contribution is humble he atones for this by the warmth of his enthusiasm.
If the result of these preliminary efforts seem discouraging, remember a good wig and suitable costume will help materially.