The microphone is your friend. I had to learn this just as much as anyone else. The microphone is there to not only amplify one's voice but it is also an enhancer. It allows a speaker or a singer to showcase his or her vocal dynamics. This is why comedians are so great with microphones. They are almost experts as using the mic for the sake of vocal variety and dynamics!
But you can't rely just on the microphone. It is up to you, as a speaker, to give the audience a taste of everything that you have. Even without a microphone, the audience deserves to hear different levels of volume and also varied inflections, pitches and tones. The microphone makes that much more alive.
Here are my tips for when using any microphone:
Test it! This is vital. If you have time before any presentation or speech make sure the mic will be your friend. This is the opportunity to adjust its levels or figure out its quirks.
Pick your poison carefully. The vast majority of speakers love to use lavaliers (lapel mics) because lavs allow them the opportunity to gesture more. If your presentation has that much going on then go for it! BUT . . . the problem with a lav is that you can't "play" with it the same way you can play with a hand-held mic. You also have to make sure that your clothes or jewelry won't rub against the lav. Note that there are other wireless hands-free options, like head sets, that may be at your disposal.
Consider having your own equipment. This is tricky. There are portable units, including a mic and amplifier set, that you can look at. But if you have a system that needs to be patched in to a venue's existing system, SCHEDULE A TIME SLOT SPECIFICALLY TO TEST YOUR EQUIPMENT. You can't try to set up about 30 minutes prior to your engagement and expect top-notch results.
Listen to yourself. As you're doing your presentation, listen carefully to how you sound. If you're too loud the audience will get annoyed. If you aren't loud enough, the results are obvious. Don't be shy about asking the audience if the volume needs to be adjusted. This is where developing a relationship with the sound person comes into play during that sound check.
Remember, make the mic your friend.
