As a newly self-employed person, you’ll almost certainly feel compelled to take on every piece of work that presents itself, because you’ll think that for some reason your supply of work might dry up next month. Finding yourself with nothing to do would be bad, but it’s almost certainly not going to happen. Finding yourself with everything to do, because you were afraid to say “no,” can be much worse.
More than just great advice on financial buffers, this paragraph from Malarkey’s latest blog post sums up freelance work in a nutshell.