Just like there are many different operations for a doctor to perform, there are many different kinds of digs. There are underwater excavations, excavations in caves, digs in the desert, rescue excavations - you name it. Then there are things archaeologists do that don't even require a shovel - like aerial survey, conservation, field walking.
Every archaeological dig is a bit different, because no two archaeological sites are the same.
However, there are some things that are common to all excavations. First you must have a site and permission from government authorities to excavate it. Before excavation, a site must be carefully researched and a decision must be made as to how much of the site will be explored. A director is appointed to lead the excavation and be responsible that the results are published. The director chooses a team of specialists who are needed to excavate the site properly.