Here are some guidelines for 12-minute talks.

This is what is going to happen: you will be sitting somewhere in the
audience while the speaker before you is talking. Try to sit somewhere
close to the front. As he/she gets near the end of their talk, prepare
yourself and get all your notes or things together that you are going
to take with you to the stage. When the talk ends and questions begin,
be ready to walk up to the front. The moment the questions end, stand
up and walk toward the stage (don't wait for your name to be called).
Try to make the microphone exchange as quickly as possible.

The moderator will then say, "The next talk is titled ___________,
by ______, _______, and ______, with [you] presenting."

DO NOT then repeat the title of your talk and the authors! Just start
talking. This is one of the most common time-wasting mistakes.  The title
will be on the first slide, everyone can see it.

If you are going to do acknowledgements at the start, DO NOT spend more
than one sentence of talking on them. At the end, you can take 2 or at
most 3 sentences. 12 minute talks are not the place to thank your friends,
family, or even your co-authors. They are already acknowledged by having
their names on the talk.

Also, I now recommend against outline slides for 12 minute talks.
Just another unnecessary use of time.

If you are nervous, you are going to talk fast. Try to slow yourself
down. If you have practiced the talk and you know you are within your
time limit, then you don't need to talk any faster.

Another common mistake is not explaining what figures are. At every
opportunity, say: "This plot shows _____ as a function of _____ for the
case of _____." If you have a lot of figures, you can't do this every
single time. BUT, if you take a little extra time to explain figures
early on, then you can save time at the end by not having to explain
them when you are trying to make an important point.

Like with all public speaking, try to face the audience and look up toward
them as often as possible. Project confidence. Even if you know that you
don't completely understand everything you are saying, the audience does
not know that!

At some point the moderator will interrupt you and say that there are
two minutes left. Don't panic - once you are already speaking, you will
be amazed how much material you can cover in the last two minutes.

At the end, if you have run out of time, just put up the conclusions slide
and say "Here are my conclusions." Everyone will already know what your
conclusions are anyway, you don't need to repeat them, and you certainly
don't need to read the words off the screen that every one can see.

Speaking of which, here is an advanced speaking tip: don't put sentences
on your slides and then read them off the screen. In fact, try to engineer
your text so that you end up saying different words to the audience, even
though they mean the same thing. This can't be done all of the time,
but it is very refreshing to have the speaker talking "spontaneously"
rather than reading from the screen. For example, you could have a bullet
point on your slide:

* Model indicates Isabel weakened by sargasso

while saying in words:

"Our simulations showed that Hurricane Isabel decayed rapidly due to
an interaction with the large amounts of sargasso seaweed on the ocean
surface."

If you do have your acknowledgements at the end, again, don't take a
lot of time with them. You can put the names up on the screen and let
the audience read the names.

Then you will take questions. A few rules:

1) Take your time to understand the question, and answer the question
that is asked...sometimes people give long explanations that don't
address the question.

2) If you don't know the answer, say it. Everyone can tell when you make
stuff up.

3) Don't get defensive about the weaknesses of your work. Say something
like "Yes, that is a good point, and we are going to try to address that
problem in the future."

A lot of these rules may sound obvious or trite but you will be amazed
how many people (including faculty) fail to follow them.