Always monitor the specific search terms that lead to result above your target ROAS
Identifying the most profitable words to target can be a bit tricky. Specific words can show up as part of different phrases and then they become separated in your Search terms report. What we do is use an automated system to break every search term up into individual words and sub-phrases. Our system works out the average ROAS for each word/phrase individually over the long-term. That way we can see the difference in ROAS between (for example) “for kids” and “for 8 year olds” . Then the next step is we try to capture the greatest market share of the best phrases.