I have had a lot of work on my plate of late, but I have noticed that clients who pay the least give the most hassles.

Clients who value good service are also the ones who keep their commitments.  It is 80/20 rule.  20% of your clients provide 80% of your returns.  You get maximum leverage from these 20% clients.

Focusing on the important clients and things that you value results in better outcome for you.  Less becomes more.