Make sure you are not running campaigns that are "Search Network With Display Select".
This option basically combines two totally separate types of advertising:
Keyword-driven search ads (e.g. "car insurance NZ") and display advertising (banner ads, basically).
These two approaches require totally different strategies and tactics ... so why would you combine them into one campaign!
It's like having a nice steak dinner, and then throwing your tiramisu on the plate for good measure. Delicious when they are served separately, but not very nice together.
Search Network with Display Select is much harder to optimize and I've seen campaigns burn a lot of money on them. Oftentimes it is well-intentioned, as Google pushes this choice quite hard.
Why? Because it makes them more money from ad clicks. No other reason.
Make sure your campaigns are Search Network or Display Network only (unless you are doing Shopping campaigns or similar).
If you need help with this, send me a message and I'll show you how to fix it.