Once you’ve been given the excavation licence, you are ready to start… thinking about more things!
Excavations should be undertaken in an orderly fashion and the best way to start an excavation project is to figure out where to dig (this should be in your project proposal) and set up proper excavation units. Units are either delineated by existing features (e.g. four walls of a room seen above ground) or by strings held by pegs. Large areas are generally divided in smaller units, often with a baulk between them (a wall of earth between units created as you dig down so that you can observe the stratigraphy of the site).
Units delineated by strings are usually set up following the grid (the longitude and latitude) of the site, which appears on the site map. The reason why archaeologists prefer to set up units in this fashion is because we can easily plot the excavation unit on the site map (which should show these gridlines). The surveyor who drew the map had to use bench marks (permanent reference points carve into a stone post, for example) to plot the site and place it along the longitude and latitude of the earth (using GPS and GIS tools). Archaeologists will use these same benchmarks to draw the excavated features or the excavation units on the site map. If there haven’t been excavations on site before and there aren’t any benchmarks, you will have to set some benchmarks and fix a grid on your map before you set up the squares and start digging.
Excavations are conducted within the unit each archaeologist has been assigned. Although I will not got into details about the actual digging techniques and methodology (there are professors who get paid well to teach you that stuff), I will say this: archaeology is not about digging holes, but removing layers of soil. In other words, archaeologists will remove about 15 centimetres of earth across the whole unit. Once this is done, you will remove another 15 cm across the whole unit again until you come across a new feature or a new locus. You do not dig holes… you peel off layers.