There are cases of writings from common people being found, but for the most part all the evidence we have to indicate specific life details is from their trash and what they were buried with. Something that has been beneficial to archaeologists is that many ancient cities were built upon older buildings creating time capsules for that time period. Most of the items that were buried were sherds of pottery. Using modern molecule analyzing techniques we are often able to find residuals of food in the sherds. From analyzing many pieces we can determine what their diet consisted of, and from their can determine their socioeconomic status based on what foods they were. From their graves, we can also determine the kind of life they lived based on their bones and what they were buried with. For example, bones showing lots of wear and signs of breaks would indicate some sort of laborer. Also, what metals they were buried with would show their economic status. If they had gold jewelry then they were quite wealthy or in they were bronze they were probably middle class. For further research on pottery and ancient city life, I would research the ruins of Carthage. For more on graves we have many notes from the cemeteries of Ur by archaeologist Leonard Woolley.