Reading on STM I've realized the importance of launching some test campaigns in order to detect what's not going to work when running real campaigns. With this I'm talking about bot test campaign. What are the other things to do that can help us to find bad placements and other elements that can ruin our future campaigns?
Ok bot-test is one, and others? 
EDIT: sorry for the title of the topic, it is incomplete and I submitted the thread without realizing. Sorry again 
I can edit the title for you, just let me know what you want it to be 
As for your question, here a few options for you :
1. BOTs - you got that one already 
2. LOW ctrs - this can identify a wrongly positioned banner spot or a problem with delivery.
3. Poor LP ctrs - can be a category mismatch , low quality traffic etc ...
4. Very High CTRs - this can also indicate bots or otherwise questionable traffic
Other than that, just watch the CVR and act accordingly 
Hi Matuloo, thank you for your reply!
You can change the title of the thread into "pre-optimisation tips?" 