Economic downturns are characterized by decreased levels of consumer purchases (especially of durable goods) and, subsequently, reduced levels of production by businesses.
You should also prepare for economic downtime in advance by having in your stock of products and services something that is not totally voulnerable for bad economic periods. Some products are always needed in a nearly equal amount all the time.
Also see if you can have some services which are demanded more when the economic climate is bad. For example will many customers effectivize, repair or upgrade their existing inventory in stead of buying new. By offering services for that demand, you can actually increase one stream of proffit.