The nine that cost the most
- No break-even target — you can't tell a good ACoS from a bad one without it. Work it out on the break-even calculator.
- Never adding negatives — wasted searches keep spending forever.
- One bid for everything — keywords convert at different rates.
- Judging on five clicks — too little data to decide.
- Ignoring ACoS until month-end — by then the spend is gone.
- Set-and-forget auto campaigns — auto is a start, not a strategy.
- Slashing bids in a panic — kills profitable volume too.
- No dayparting — paying full bids when nobody buys.
- Ads pointing at a weak listing — you pay for clicks that bounce.
The one habit that fixes most of them
Nearly all of these come down to consistency — doing the weekly cleanup, every week, with data not emotion. That is exactly what automation is good at: AIAdKing runs the discipline nightly with a logged reason for every change, so the slow leaks never reopen.