I have several campaigns running and they're profitable, but not as profitable as they used to be (my goal is to keep the ACoS around 30%). I think you covered the main points.

The overall tip is that AMS isn't a "set it and forget it" type of system. You have to constantly optimize and tweak your campaigns. Also, since the reports are delayed by several days to weeks, it can be difficult to see the effects of changes, so don't make any hasty decisions.