Oral and poster presentations must offer technical information of benefit & interest to attendees. Marketing / commercial presentations are not appropriate.
Make sure you follow the deadlines and direction given by your session chair.
For oral presentations make sure your power point slides are of a high and visible to the audience. A frequent mistake is to use a font that is too small. Practice your talk and make sure it fits within the allocated time and you leave a few minutes for questions.
Poster presenters must make sure their posters fit within the specified dimension. The more time you spend developing a quality poster the more likely you are to attract attendees to your poster. Make sure you stand by your poster so you can discuss your work with attendees during the poster session.