I’d like to give a brief outline / preview of my presentation.
First I’ll explain / provide…
I shall begin with …
Then / Second / Secondly I plan to focus on / talk about …
After that / Third / Thirdly I want to illustrate / demonstrate…
… will be presented later / afterwards.
Finally / Lastly, I hope to …
I have divided my presentation into… parts.
The first is … The second is … The third is …