Split Infinitive

Maybe when you started learning English, one of the rules you learned was don’t split the infinitive. That means don’t put a word between “to” and the verb. For example:
“He told me to not give up” has a split infinitive, but:
“He told me not to give up” avoids that.
This rule isn’t very strict, mostly because it doesn’t cause any communication problem. In fact, most people don’t care if they hear a split infinitive.

However, there are situations where the split infinitive is useful:

A: “I’m going to tell you how not to talk to your boss.”
B: “I’m going to tell you how to not talk to your boss.”

Sentence A means I will give you examples of an unsuitable way to talk to your boss, so that you can learn from them and avoid causing trouble.
Sentence B means I will show you how to avoid speaking to your boss completely, so that you never need to talk to him/her.

Here is an example on the BBC website: How to not embarrass yourself in a British pub