This site is about preparing and preaching sermons.

  Dr. Broadus states the things that are requisite to effective delivery.
  They are as follows:
  "Have something to say which you are confident is worth saying; scarcely anything
  will contribute so much as this confidence, to give dignity, directness, ease,
  and power to delivery.
  Have the treatment well arranged, not after the fashion of an essay, but with the orderly
  and rapid movement proper to a discourse.

  Be thoroughly familiar with all that you propose to say, so that you may feel no uneasiness;
  for the dread of failure sadly interrupts the flow of thought and feeling.
  Think it all over within a short time of the hour for speaking, so that you may be sure
  of the ground, and so that your feelings may be brought to into lively sympathy with the subject;
  it is, however, best immediately before speaking to have the mind free from
  active thought,maintaining only a quiet, devotional frame.

  Let the physical condition be as vigorous as possible.
  In order for this, seek good health in general; take abundant sleep the night before speaking;
  at the meal before speaking eat moderately, of food easily digested,
  and if you are to speak immediately, eat very little; and do not, if it can possibly be avoided,
  exhaust your vitality during the day by exciting conversation.

  A healthy condition of the nervous system is surpassingly important, not a morbid excitability,
  such as is produced by studying very late the night before, but a healthy condition,
  so that feeling may quickly respond to thought, so that there may be sympathetic emotion,
  and at the same time complete control.

  Above all, be yourself.
  Speak out with freedom and earnestness what you think and feel.
  Better a thousand faults than through dread of faults to be tame.
  Some of the most useful preachers, men in a true and high sense eloquent,
  have had grave defects of manner.

  Habitually correct faults as far as possible, but whether the voice and the action be good or bad,
  if there is something in you to say, speak it out.
  And by all means let there be no affectation or even artificiality
."

 The voice is the preacher's greatest instrument.
  Nothing else in a preacher's physical condition is nearly so important.

  Broadus also says that improving the general health will also improve the voice.
  He also says that muscular exercise and especially that which would develop the chest
  would promote an erectness of position.

  He adds, "Singing cultivates the voice in almost every respect and probably to a greater extent
  than anything else except actual speaking.
  It is on many other accounts also very desirable that a minister should be able
  to sing... young ministers and those preparing for the ministry should take much pains
  to learn to sing....
  Reading aloud is also of good service in cultivating the voice.... A proper management
  of the voice in all ordinary conversation, is a matter of the very high importance.

  As in politeness and as in style, so in the use of the voice (and also in action),
  it is impossible for one to do really well on special occasions who is habitually careless and slovenly
."

  (Slovenly: "Negligent of neatness especially in dress and person; habitually dirty and unkempt.
  Such as "slovenly appearance
".)

  Broadus gives a few simple hints on managing the voice when preaching.
  1. Do not began on too high a key.
       If a preacher becomes too passionate in the early part of a sermon, he should not allow his voice
       to reach its full force but reserve its highest power for some later, culminating point.
       Broadus says, "Long passages of brawling, relieved only by occasional bursts in to
       a harrowing scream, are in every sense hurtful to all concerned
."

  2. Do not allow the voice to drop in the last words of a sentence.
  3. Never fail to take a breath before the lungs are entirely exhausted.
       It is good to keep the lungs well filled.
  4. Look often at the hearer the fartherest away from you, and make sure that they hear you.
  5. There should be variety -- a variety, of force, and of speed.
       Monotony is utterly destructive.
       Emphasis requires much attention.
       In speaking, a correct emphasis will be spontaneous whenever one is fully in sympathy
       with his subject.

  Broadus also says that a gesture is much more expressive than any number of words.
  He quotes Dr. R. L. Dabney about the use of gestures.
  Dr. Dabney says: "To say, 'Leave the room,' is less expressive than to point to the door.
  Placing a finger on the lips is more forcible than whispering, 'Do not speak.'
  A beck of the hand is better than 'Come here.'
  No phrase can convey the idea of surprise so vividly as opening the eyes and raising the eyebrows.
  A shurg of the shoulders would lose much by translation into words
."

  The preacher should always look at the hearers.
  It would be difficult to overstate the importance of this.

  Posture is also important.
  In walking, standing, sitting, riding, the preacher should be careful to acquire the appropriate posture.
  One of the most common faults of preachers is leaning on the pulpit.
  The preacher should resist the temptation to do this.
  His body should be erect.

  The arms should at first hang easily by his side.
  Folding them on the chest is a gesture that should be rarely used.
  To place the hands on the hips with the fingers forward suggest a sort of defiance.
  To clasp the hands behind the back, though not offensive, is scarcely graceful.
  To put them in the coat pockets is inelegant, and Broadus says to put them in the trousers' pockets
  is vulgar.

  It is natural that the arms should at first hang easily by the side (with the palm towards the body),
  until there is occasion to move one or both to gesture.

  Broadus says that it is not natural for a preacher, if at all animated, to stand perfectly still,
  and it is the important not to fidget about or to walk the platform like a tiger in his cage.
  He suggests that between these extremes, a preacher will change place more or less freely
  according to temperament, circumstances, and taste.

  To stamp the foot may sometimes naturally express indignation or certain other vehement feelings,
  but is apt to suggest an impotent rage, and is not very becoming in a preacher.
  Movements of the body, such as rocking to and fro or swaying from side to side, are almost always
  to be avoided, and bending far forward is very rarely proper.

  The head has a variety of appropriate and expressive movements, but one must beware
  of awkwardnesses, extreme vehemence, and monotony.

  Avoid monotony.
  The same gestures repeated again and again is somewhat a common fault.
  The frequent recurrence of a word, a tone, or gesture, is always a fault and, as soon
  as the preacher becomes aware of it, should be carefully avoided.

Adapted from On the Preparation and Delivery of Sermons by John Broadus, pp. 335-356