Portfolio presentation is performance. Consider each piece in your portfolio to be a short story. Write the story about each piece as a script in a beginning, middle & end manner or a context, action, & results approach. Memorize the script. Rehearse the presentation – preferably in front of a mirror – until you can tell each story in a casual, articulate manner.
Passion, knowledge and confidence (and your great work, of course) are the keys to a memorable presentation.