My contribution would be to make sure your channel plan is accurately built. All digital channels should be set to the proper modulation, all DOCSIS channel set as such, etc.
Use all 12 spots on your tilt and miniscan screens, to get a full picture of the flatness of your signal.
Make sure you have good quality coax jumpers and keep the connections tight. Avoid using pushons for anything other than quick level checks. DQI, ingress tests, etc must be done with snugly threaded connections.