One tip would be to post questions like this only ONCE, in one, single sub-forum. As to photographing people, my main tip would be not to worry so much if a person steps on your feet, since it hurts MUCH,much less than when a horse steps on your feet. Keep the subjects happy, by offering small treats such as sugar cubes and sweetened grains...no, wait...that's horses...doggone it....
AH, well, for people, one tip is to tell them that not every shot needs to be a big, toothy smile, and that not every shot needs to be perfect. Tell them that, since you are shooting digitally, that a slightly "off" expression is no big deal, and that there's a wide,wide range of expressions that are fine. This single pre-shoot pep talk really does help, a LOT, in my experience. Many people want so much to "please", and to "do well", that they get tense. Telling them that not every shot needs to be just perfect can go a long ways toward setting people at ease.