Yes, I know wraith, I had to be prepared for extended periods of time with no income or work. Sometimes I was and sometimes I was not. Or to spend the time and money preparing and getting to a job, only to be turned down due to a customer's whim or weather or some other reason. Or doing a large job that takes a couple of weeks and to wait, minimum, 30 days for payment. Here in the usa, the best advertisement is by way of the yellow pages, (for my type of work) and they know it, very expensive. Word of mouth happened a lot, but the phone rang more via the yellow pages.
edit- and yeah I got burned on a few jobs for a substantial amount of money, not many times but enough to demand cash in advance from certain types of corporations, or avoid them completely