Give your objectives (purpose, aim, goals)
The main purpose of an informative speech is to have the audience understand and remember a certain amount of information. You should thus have two purposes: a general purpose and a specific one. The former is to inform: to give an overview, to present, to summarize, to outline; to discuss the current situation or to explain how to do something or how something is done. The latter is what you want the audience to take away with them after listening to you, what you want them to do, what they should remember.
My purpose in doing this paper is to give you a solid background on the subject of oral presentation so that in the future, at the INT or elsewhere you can deliver a successful speech in front of a group.
What I would like to do today is to explain...
to illustrate...
to give a general overview of...
to outline...
to have a look at...
What I want my listeners to get out of my speech is...
Once you have established your specific objectives you may go on to formulate your content.
Announce your outline.
You want to keep the outline simple so 2 or 3 main points are usually enough. Concerning grammar the headings of the outline should be of the same grammatical form.
I have broken my speech down/up into X parts.
I have divided my presentation (up) into Y parts.
In the first part I give a few basic definitions. In the next section I will explain In part three, I am going to show...
In the last place I would like/want to give a practical example...