get on (someone's) good side
To become the object of someone's favor; to do something that causes someone to be pleased. The superintendent is a powerful woman in the school district, so be sure to get on her good side. I'm hoping to get on John's good side with this cake I baked for him.
get on someone's good side
Win someone's approval or support, as in Kate offered to walk the dog in order to get on her aunt's good side. [c. 1930] Also see in good with.