If you are not familiar with the use of microphones you might find the following of interest and assistance. It may also help you to avoid incurring the wrath of the tech crew. Note too that due to a handy little feature on most mixing desks called PFL (Pre-Fade Listen) the tech crew can hear you even when no sound is coming out of the PA speakers so don't be too rude about us - we might be listening!
Microphones are delicate pieces of equipment and the good ones are expensive. Most of the mics used at conventions come into this category and some are owned by various members of the tech crew who will be grateful if the mics are returned undamaged. Obviously it is not a good idea to drop a mic or to beat your neighbour over the head with it, but some types can be damaged by surprisingly small shocks so try to avoid bumping a mic unnecessarily or tapping it to see if it is alive. To test a mic either click your fingers near to it or speak into it in a normal voice. (You do know why techies say "one, two, one, two" don't you? That's because they can't count as far as "three"). If nothing appears to happen, don't keep shouting louder and louder. If the mic is not live, it's not live and all the shouting in the world won't make it work any better, but you'll get a nasty shock when the techie finds the appropriate channel and switches things on. Please don't blow sharply into a mic - it can damage the mic capsule and will certainly produce a horrible noise from the speakers. Furthermore a loud noise can damage the hearing of any techie who is wearing headphones at the time. Other than a lapel mic, a microphone should be positioned slightly below the level of your mouth, which avoids the "popping" caused by plosive sounds like "B" and "P", and normally about a foot away from you, although most mics will pick up adequately up to about 2 feet away. You don't need to make love to it, nor to grasp it tightly to prevent its escape. Whatever type of mic you are using. speak in a normal voice. Unless you have a very quiet voice indeed the volume can be adjusted by the sound tech. Don't try to alter the volume of your voice if you think you are too loud or too quiet over the PA - the poor techie will go mad trying to keep the output levels balanced. Try too to resist the temptation to indulge in dramatic shrieks or other sound effects, for the sake of everyone's ears (and nerves). If you need to sneeze or cough, either turn away from the mic or put your hand between you and the mic. It reduces the noise and stops the microphone from catching your cold. With any type of mic, try to remain a consistent distance away from it since this makes the techie's job of balancing the sound much easier. Some mics are very directional and will only pick up sound in a narrow area in front so you will need to speak directly at it, not off to one side. Most of the mics used at conventions will allow you a reasonable amount of movement however, so provided you don't turn away completely you should be fine. Don't fiddle with any switches that you might find on a microphone. The tech crew should have set it correctly before handing it to you and you will incur their wrath if they find that the reason no sound is coming out of the speakers is that you have turned the mic off! Furthermore, switching a mic on or off when the channel is live can make horrible noises.
LAPEL & LAVALIER MICS
If you are presented with a tiny microphone mounted on a cord, simply hang it around your neck. If it is mounted on a clip fasten it to your clothing somewhere on your chest but not directly under your chin nor down around your navel. Try to keep it away from dangling jewellry as the noise is clearly picked up by the mic. Once it is in place, forget about it. Don't try to speak at it or hold it in your fingers. Provided you don't turn your head completely away from the mic it will pick up your voice adequately - that's what these mics are designed for; normal movements are not usually a problem. It's worth thinking about which way you will be looking most of the time and positioning your mic accordingly, eg if you are on the far left of a table and will be tending to look towards your right at the rest of the panel, pin the mic on your right side. Don't forget you are wearing it when you get up to leave the stage after the event.
Note that many of the comments here are also applicable to microphones which are attached to a podium. Take care that you don't hit the mic with your notes when shuffling your paperwork or when indulging in expressive gestures. Most of the mics (other than lapel mics) used by the tech crew will work perfectly well at a distance of up to 2 feet provided you speak towards the mic. These microphones are usually fairly directional, ie they pick up sound clearly from directly in front of the mic, less from the side and almost none from behind so the audience is not picked up. They WILL pick up - very clearly - bumps and knocks on the table which are transmitted through the stand. This includes tapping pencils and drumming fingers, also plonking a glass down heavily on the table and kicking the table legs. These noises can be intrusive and irritating to the audience. The tech crew will try to provide enough mics so that you don't need to pass them along the table, but if you need to move the mic please do so gently and try not to bump the stand down too heavily.
Easy. Position yourself 6"-12" away from the mic, which should be slightly below the level of your mouth (see above). If the stand needs adjusting, best technique is to adopt the professional actor's approach (ask me about a certain Star Trek actor some time) and let the tech crew do it for you. Try not to wander about too much while you are speaking. With a highly directional mic you can easily wander out of the area of sensitivity, and if you alter your distance from the mic too much it will affect the volume (and drive the techie to despair as she/he tries to keep the sound balanced).
If it's a radio mic you have no cable to worry about so just take the mic and talk at it. The tech crew will work out which channel it is on eventually. If there is a cable, take a small loop of it in the hand you are using to hold the mic. You've probably seen professional vocalists do it - it's not an affectation, it relieves the strain on the connector. Hold the mic firmly and try not to fumble with it as this makes noise. Try to hold the mic a consistent distance from your mouth; about 6" is usually fine. Remember that if you wave it around in the air or hold it behind your back it won't be able to pick up your voice properly. (Ask me about that Star Trek actor again!) If you hit something with the mic the tech crew will deal with you later.
Most of the above comments apply equally to normal mics and radio mics. The one thing to watch out for with radio mics is the aerial which hangs from most of them (usually a little flexible black plastic tail). If you break it the mic won't work and it can't easily be repaired. The sort of radio mic which has a transmitter pack attached to your belt or in your pocket can be sensitive to static so if you know in advance that you will be using one, try to avoid wearing man-made fibres. Unless the technician shows you a switch and tells you to use it, the mic will be live when you get it. Even if your voice isn't being broadcast over the PA system the tech crew can hear you. This is useful in that the tech crew can listen for you to tell them when you are ready, (just say something appropriate to us) but it also means that they can hear you at other times, so take care you don't indulge in any potentially embarrassing conversations or activities. Even if YOU are not embarrassed, I might be! Don't forget to return the mic to tech afterwards.
If something goes wrong, the mic doesn't work or horrible noises come out of the PA system, panic ye not and keep quiet. The tech crew will panic for you and fix things as fast as they can and meanwhile the audience will blame the tech crew, not you. Buy us a drink later - mine's a malt whisky!