Thou shalt be gracious above all else, even if provoked.
Thou shalt do thy homework by learning something or use about the subject of your introduction, and by pronouncing all names, titles, etc., correctly.
Thou shalt practice moderation, neither damning with faint nor fulsome praise.
Thou shalt leave trumpeting to Gabriel and not toot thine own horn, nor hawk thine own wares.
Thou shalt never do a routine, unless expressly asked to do so by the producer of the event (and maybe not even then).
Thou shalt gather the energy in the room and direct it toward the Featured performer(s). Under no circumstances shall ye gather than energy for thyself and devour it.
Thou shalt give the appearance of listening and enjoying the show, even while preparing for the next introduction.
Thou shalt not strive unduly for eloquence (the better to gather admiration for oneself).
Thou shalt not read aloud from the program, nor consult thy clipboard, scrap of paper or palm, except discreetly, when affecting en introduction.
Thou shalt do thy job: get on and off with alacrity. Warm up the audience, tell them what gives and provide a pleasing wrap-up, which occasionally includes triage.
Things NOT to do
Being rude to the performer, the audience or both.
Neglecting the fundamentals: that the sound works, the performers have a chance to check it, that amenities (water, etc.) are present.
Failing to find out what is important to the performer, and finding a way to work it into the introduction.
Failing to inform the performer of time restrictions. ALSO, allowing the performer to exceed that limit by more than five minutes without talking turkey afterward; AND allowing that performer to exceed by more than eight minutes without interceding during the performance.
Playing favorites In introductions: rewarding your pals, and barely acknowledging those who have not garnered your admiration.
Making insider-only remarks; OR dwelling upon ones own relationship with the performer, thus making the audience feel that a terrific party went on, somewhere, without them.
Making apologies for anything during the evening.
Get to the venue on time.
Accept and understand that the emcee decides the show order, and that everyone believes that s/he has the best performance to end the show.
Resist the temptation to correct small errors In an introduction ("No, no I live on Third Avenue, not Boulevard); avoid getting into a spat over the emcee's choice of words to describe you. (A VERY useful tool is to give the Emcee a easily read piece to help introduce you. See "Introduction Sheet" section.)
Tell the emcee what you are going to do. It unnerves an audience for you to tell them that you just can't decide what routines you're going to do for them, and then to stand there thinking really hard before you choose what to do and get started with the routine.
Indulge the emcee's obsessive nature, and stay within his/her sight during the show, before you go on.
Stay put while you're being introduced, instead of walking up behind the emcee while s/he is still introducing you.
Refrain from making any self-serving announcements ("In case you didn't know, my new tape just won the Queen of the World Award and you can still get a copy?')