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...