Watch your opponent playing beforehand if you can. Few players have no weak points, and it may be of great service to you to know his.
Be careful to get thoroughly warm before you go into court. Without this precaution, one is very apt to lose the first game or two, which perhaps one can ill spare. Every man must judge for himself how much warming-up he needs, for he must not carry it to the extent of tiring himself at all before a long match.
Do not neglect to find out who is to umpire for you, and if you think him incompetent, object to him before the match. It is sufficient if his manner is annoying to you, as you need all your attention for the game.
You will be constantly umpired out of games, and even matches, and the annoyance is much less if you feel that you have done all that was in your power by having good men to umpire.
Learn in a match to say nothing about the decisions, and to think of them as little as possible, else one bad decision may lose you many strokes.
Be careful about the minor details of the game. See that your racket does not want a new string and that there is no nail at the end of the handle that may hurt your hand. Have a second racket ready in case of accidents, and have it as like the first as possible.
Look to your shoes, and see that there are enough points in them, and that they are not clogged up with dirt.
If you want something to drink in a match, brandy with a little water in it is the best thing; soda is too bulky. A slice of lemon is very pleasant in hot weather.
If the handle of your racket slips a little, lemon-juice rubbed on it makes it easier to hold. With an octagonal handle, I believe that any slipping of the racket arises from some fault in the way in which it is held.
As to eating and drinking, I believe in living just as one is in the habit of doing, using stimulants and luxuries in moderation.