This is a GradHacker by Cory Owen, PhD grad student in Educational Leadership at University of Houston, @coowen.
Practice makes perfect, so why should your presentations be any other way? You can do a spin on Terry's idea and record your presentations online  to critique yourself which can be very helpful. But if you're anything like me, there's just something cringe-worthy about seeing yourself on screen. I tend to over-analyze all my "isms" and outfits and weird hair and shadows and. . .you get the point.
So, to protect my own fragile ego, I like to have practice runs of my big presentations in more casual events--but not where the entire audience is made up of my friends and family. Brown bags are a great resource for practicing your presentation, building your confidence, and sharing your research. We have them on campus all the time and they give you an opportunity to present your materials in a somewhat casual, but somewhat formal setting. Sometimes you'll get some friendly and familiar faces in the crowd, but more often than not, it simulates the "real thing" in a more effective setting than sitting in front of a mirror and practicing your speech.
Plus, as busy grad students, we're often finding ourselves without much extra time, so doing your presentation during a meal time is a perfect way to kill a few birds with one stone. You, as the presenter, can get the practice you need for your presentation while getting some helpful feedback. The audience gets to learn all about your interesting research while eating their lunch.
I especially like brown bags because if you're in a supportive community (which I hope you all are), you'll see the faculty come out and give some very helpful tips on how to improve your presentation. You can let your audience know ahead of time that this is a practice run for a conference, and ask for any suggestions about the presentation itself rather than just the content.
This kind of dry run is so helpful in calming the butterflies in the stomach when you go for your actual conference and it helps to build confidence in your own presentation skills as you practice your pauses, hand motions, and eye contact.
So what can you do if your department doesn't have Brown Bags? Check out other departments in your college that have similar themes. You can also propose to do a brown bag for your department even if it isn't a formal event that is already set up.
What is your experience with brown bags? How do you prepare for presentations?
[Image by Flickr user Jeffrey Beall  and used under Creative Commons License]