Think of a presentation as something between an abstract and a journal article.
Journal articles are usually written along a strict formula, with certain information given in specific places:
- what do you study and why is this relevant
- what is the theoretical background and what other research has been done or is related
- what is your hypothesis
- what are your methods
- what are the results
- how do you interpret the results in the context of the other research
- what future research do you recommend
The abstract is a condensed version, explaining only what you studied, how, and what the results are.
A presentation is like an extended abstract. You don't go into the theoretical background (if it is common knowledge among your audience), don't report any of the other research (unless you are doing a replication), and you give only a minimal interpretation at the end, leaving this to the discussion. So all you need to do is
- open with a few sentences on what you did
- explain your methodology in a concise but understandable way
- give your results
- give some hint at an interpretation that will stimulate a lively discussion
You can do that in five minutes. Use another five minutes to add interesting tidbits, some jokes, and allow the last five minutes for something to go wrong and take up some of your time. Plan to speak only ten minutes, and you will speak fifteen.
Make sure your graphics and visual text are easy to scan and attractive and complement your talk, not repeat it. People can "read" short text and look at graphics while they listen to you saying something else. So don't bore an audience of intelligent experts with unnecessary redundancy. At the same time your visuals must be as clear and pleasing as if you were illustrating a children's book on the topic.