When we communicate there are two main reasons we attempt it: to inform or to persuade.
When we communicate to inform we are attempting to teach. The primary concern under these circumstances is to make clear and easy to recall those things that will be necessary for the listener to understand. We all are teachers and we are called on to explain things on a regular basis. There are several questions that would be useful to ask yourself before you begin.
1) What do they need to know?
2) What do they already know? Be careful here or you may be offensive.
3) How will they best be able to follow and remember necessary information?
These questions are useful no matter how large or small the audience is. It helps if the person(s) seeking the information think/believe that you know. The more certain they are that you do know the more likely that they will focus their attention on what you are saying/doing.
When we communicate to persuade we are attempting to alter their position, change their mind, modify their behavior and so on. Here we must put together information, some of which they probably already know and then organize it so that certain conclusions seem to flow naturally from the information. You will still be a teacher, but now you care about the outcome and you want them to change. The same questions listed above apply now as well. This time you will describe the outcome you value and if time permits describe outcomes that are not as desirable no matter how tempting.
The more they believe that you know what you're talking about and the easier it is for them to change the more likely they will focus on and recall what you have said--and the more likely they will change in the direction you had hoped for. Again, the more they perceive you as being informed and clear thinking the more likely they will focus on and accept and spend less time questioning what you say. If they see the change as being useful, fulfilling, desirable, dependable and reasonable they may make a two changes: change in behavior (vote for you) and change in mind (believe that you have given them a truth to live by.)
We use both forms of communication every day. We want those around us to know more about us and we want some of the them to accept us as friends and cohorts.