Language
You should
use a language which is appropriate for your audience, as your aim
is to be understood. Hence you should have an idea of the type of
people that are going to be attending the event.
Therefore,
you shouldn't use terms and expressions that a proportion of the
public might not understand.
You
should only use technical terms if the audience knows their meaning.
If
you use abbreviations or acronyms you need to be certain that the
public knows what they mean, if not then you will have to explain
their meaning.
You
shouldn't use foreign words, unless there is not an equivalent in
Castilian, in this case you need to know how to pronounce them correctly.
You need
to avoid seeming pedantic (as this annoys the public).
The objective
of the speech is to win over the public with your ideas, not try
and astound them with your vast contol of the language. You have
to run away from stilted language and complicated phrases.
You should
avoid using "certain phrases" that are sometimes used in
a conversation without the speaker being aware of it (you see, understood,
you get me, etc).
The effect
that is gives is terrible (all you have to do is listen to yourself
in a recording to realize how bad it sounds).
The rule
which should be present throughout the speech is simplicity.
If a
reader is reading a paragraph and they do not understand it they
can re-read it, however in a speech the listener can not do this,
therefore you have to help the audience understand.
The
language should be precise and direct, with short and simply phrases,
using simple tenses.
In
short, the audience appreciates simplicity and hates pedantry.