1. Never assume anything without supporting data. It is not unusual for search marketers to have assumptions or intuitive feeling. I was once told "You have to assume something is true for others to be explained" but without data, it is advised to not take any major action.
2. Identify your top performing keywords: Depending on the account's performance history, conversion type, quality score, landing page and other factors, there are sets of keywords that work better than others. It is important to know these keywords and how much they could be paid to still maintain the profit margin.
3. Constantly monitor changes in search volume: Change in click volume could be due to internal or external factors, but regardless of the reasons, click volume can provide prediction of future changes of the market.
4. Do not ignore other channels: It's hard for search marketers, especially paid search, to look past the click/cost/conversions data but a lot of times, changes in campaign performance are due to influences from other channels.
5. Do frequent deep-dives: We don't always find valuable insights from digging into data but each time a deep-dive is done, search marketers will understand the campaign performance a little bit more. It is definitely worth it.