The most critical decision you will make will be choosing the topic for your talk. Don't get stuck with something lame. That'll kill any efforts. Get a fabulous topic, and half of the work already is done. Make sure you have an angle on it, too. Don't be too broad, or you'll sound encyclopedic, no matter what you do. Look for something you are interested in, as well as something that you think will give other people a charge, preferably something with a bit of conflict at its core. A good debate always livens up reports.
Do as much research as you possibly can. Be the expert on your topic, from the angle you are pursuing. Don't just know it long enough to create a PowerPoint slide, know it, like you might tell someone about it at a party. Know it, like two years from now, you still will know it.
Determine the best way to tell the information. What flexibility for creativity do you have? Could you do something really wild and fun? Could you do something light and interactive? The broader the range, the more you should try to create a format that plays to your subject's strengths.
Use stories. Human beings are narrative animals. In other words, we learn through stories. We interpret through stories. We live through stories. Our lives are basically one anecdote after another (some more interesting than others). Take the time to learn the stories of your subject. What interesting tales can be woven together to tell this piece? Plus, those also are a lot easier to memorize than page upon page of factoids.
Use visual material to complement your words. People want to look at something, and, no matter what you look like, they probably don't just want to sit and stare at you talking. So give them something to look at, something evocative and engaging. Graphs are good. But so are images that illustrate what you are talking about. If you have something that needs to be described, do that, but also show it.
Prompt your audience. Get them talking. Get them asking questions. It will give you a chance to demonstrate your authority. It will take the pressure off of you to entertain, and it will force your audience to give as much as they are giving.
End strong. Don't just peter out. Come up to your conclusion like it's the finale of a concert. Big, loud and definitively the end.