I bombed the first time I did a big presentation.
It ruined my weekend because I thought it was going to be awesome and it definitely wasn't. After I got over the embarrassment I forced myself to focus on the communication side of presenting. For a year I didn't even use a computer or projector. It was like the "wax on, wax off" approach to presenting, but I had to learn how to hold an audience's attention.
When I felt like I knew how to communicate better I started using slides and presentation software again. "Presenting (In A Nutshell)" is a brief overview of what I've learned through the years and how I approach presentations at their most rudimentary level. It still works for me today.