For you maniacs who insist on being IN your own films, forget about trying to direct the film at the same time. You need an Assistant Director to take over that responsibility when you're on camera. These are general purpose crew members and are essential. They are, in fact, the glue that holds the entire day's shooting together. You have a date, you're assembling the requirements, now arrange transportation, food and all ancillary details of the shoot.
Most shoots take all day and go into the night.
Assume coffee and donuts, a good lunch, and something to make it through the night if necessary. Assume to pay for outstanding transportation costs. If a number of vehicles are involved, take care of all the logistics regarding who drives who. Print a calender to show everyone what will be shooting when. Be flexible and pace yourself.