If you cannot place your back to a wall, tent, or some other object which will keep visitors from your back, then be sure to stand or turn your chair so that you are at least facing them in front at all times. Take note of your surroundings. If you find yourself in an unsuitable location, take a few moments to speak to the event coordinator about your needs. Most are more than willing to accommodate you. When addressing a crowd, be conscious always of your voice.
Projection is a theatrical art that is indispensable in the field.
When we combat noises of camp, muskets, traffic, etc. Look into some basic theatrical courses at your community college or your local theatre if you are unfamiliar with projection. Be aware that some visitors are confused by first person. They are unsure how to deal with a person of the past. With this in mind, it may be occasionally necessary to drop out of character in order to help the visitor reach a full understanding.