don't make waves = don't interfere, don't cause problems
الإجابة بحثت عنها بقاموس للـ idioms
وهذي المعنى من القاموس:
make waves
to change an existing situation in a way which causes problems or upsets people.
example:
Our culture encourages us to fit the norm and not to make waves.
Don't stick your neck out = don't take unnecessary chances.
وهذي بعد من القاموس لقيتها:
stick one's neck out (for someone or something)
Fig. to take a risk.
e.g.
Why should I stick my neck out to do something for her?
To stick your neck out means to take a risk or stand out in a way that could result in adverse consequences, so the idiom don't stick your neck out is advice not to put yourself at risk, or not to do