Be in tune with your local community. I get wind of problem clients AND problem partners or suppliers long before we're even on each others' radar.

Try and surround yourself with people you trust so when someone says "xxxxxx is super unprofessional" you know they're being legit and they're not just trying to cover their own back or running saboutage.

My main mistake was not paying attention to adjacent businesses and underestimating how destructive they can be. Who's in your office block? Who did you graduate with? Try and identify problem people in these groups and pivot away from them