I think I need to elaborate on a few things I posted earlier.
One thing that can ruin a talk is the misuse of the microphone. I have already said that it is essential to use one if you can, because there might be people who are hard of hearing present and you might think your voice is louder than it is. However, if you are not used to using a microphone, try it out before you speak. Ask someone to show you how it works and how close you need to stand to it.
If you have to hold it, ask someone to go to the back of the room and tell you if you sound right. You need to know how to hold it and how far from your mouth. Most mikes should not need to look as if they are being eaten while in use! If you are too close to it, the sound can be distorted and your words unclear; if you are too far away it will not do any good, except to get you stressed out with worrying about using it.
I always think it rather amusing when a speaker gets an negative answer after asking, “Can you hear me at the back?” But you do need to check that you can be heard and it is not a good idea to wait until you have been introduced and your audience is waiting expectantly. Arrive at the venue early enough to test, not only any equipment of your own, you might be using but also the microphone provided.
A microphone that is fixed is usually one that is directional, picking sound up from a distance of about two or three feet away and so you should be able to stand up comfortably. It should not be necessary to lean on the lectern/desk/table to get close to it – I have seen it done. You might do your back in and be unable to stand up again afterwards!
Keep speaking towards the mike. Do not turn away from it while speaking. If the mike is fixed and you need to point to a chart or picture you have on a board, give the information first and then point to the relevant item. You might have to repeat yourself afterwards to make it clear. If you turn away from the mike, nobody will hear you. This might seem obvious but I have lost count of how many times I have seen it happen. When using a laptop to control a presentation on screen, the same applies. Ask for a table, so that you can set up your laptop in order to be able to control the presentation while facing your audience. In the days of slide projectors, it was necessary for the speaker to sit with his or her back to the audience but the sensible speakers always asked a friend or relative to change the slides for them.
Unless the circumstances are exceptional, always speak directly towards your audience. Even though your voice is heard, your back will not communicate as well as your face! Do not underestimate how much even those with good hearing, lip-read and being able to see your mouth move is important. They will be able to pick your words out better if they can see you and, if they can see your facial expressions that suit the subject, they will be even more attentive and find the topic more interesting.
Even better still is a roving radio mike that you clip on. If using one of an older kind that has a box, one that needs to be put in a pocket or clipped on a belt, make sure it is fixed carefully to you before the meeting and the wires are tucked away where they cannot catch on anything. I have seen mikes pulled off completely when the speaker moves across the room, catching the wire on an item of furniture. This involves an embarrassing time of rescuing the mike and reattaching it, if possible and allows the audience to be distracted. After such an incident it can be hard to settle into the subject again.
The safest way to use such a mike needs a bit of time to prepare but is much better: attach the box by its clip to a belt or trouser/skirt waistband or even better, a belt under your outer garments. Feed the wire up inside the back of your shirt/blouse or just under your jacket, bringing it over your shoulder and out through the neck, attaching it to the mike somewhere around the neckline, pointing it towards your neck and voice-box. This allows for complete freedom of movement and the wires will not be able to catch on anything. If wearing a jacket, use the lapel. A firmer jacket is best for this. Many modern ladies’ jackets do not have stiff lapels and mikes can flop over when they are attached to soft material.
Do not attach the mike to any part of your clothing that moves much. Attaching it to a lapel or the top of a blouse or dress that is close to a big tie or a piece of jewellery, which scrapes on it, can mean strange noises occurring throughout, your listeners distracted and anyone using a loop system going crazy! When attaching it, test it in several places below your neck to find the best position. It needs to be secure and immovable and pointing towards your voice box, not down towards the floor. Ask for help, if you are not sure.
If you are asked to use a really modern mike that attaches to your head, you need to ensure it is on firmly, so ask for help. These are used much more in stage productions rather than talks, so it unlikely that you will be asked to use one.
Some of these suggestions might seem obvious but it is amazing how often amateurs do not think of them.