Budgeting on a Fluctuating Commission

How do we budget and save on a fluctuating commission? My husband works on 100% insurance commission. Some months he makes enough (or more) to cover our essential bills, and other months there is no money. He works his tail off, but in the end you simply cannot make people buy insurance, whether they see the value in it or not. We have gone through our savings and what little retirement money was set aside. Probably not the best plan, but it is reality. He's in the market for another job, but in the meantime we need to know how to budget and save. Anyone have experience in this area? Side note: I work as well, and bring home enough to cover small things like food & gas. All other items (rent, utilities, insurance, etc) come out of my husband's income.