In my opinion the key to an effective approach to a pitch presentation comes down to preparation. For instance working out a plan of how you will present your work and then practising what you will say during the presentation.
Generally you will show your work in the order you did it, like have initial research first. Then following this up with initial designs, followed by your improved iterations as you go. Finally concluding with your final work.
As you are presenting you’ll more than likely be listening to feedback as with most client artist talks, and generally the presentation will have a lot of back and forth. So you should know your work, research, designs, and so on thoroughly so that you can have a conversation with the art director, or whomever you are presenting to.
The presentation should be interesting, memorable and to the point. As well as using appropriate body language in order to make the viewer feel at ease and project confidence in yourself and therefore your work.
At the end of the presentation its important to allow for questions, making sure you have the answers or can give the impression you have the resources to answer said question. And to leave contact details and reference to your presentation, and generally just leave a good final impression with the viewers.
And finally establish when to follow up with them about the project being green lit.