know on which side your bread is buttered

know which side (one's) bread is buttered (on)

To know how to best ensure one's success. I know which side my bread is buttered on, so I was very nice to the recruiter and promptly sent her a thank you card after our interview.
See also: bread, butter, know, side

know on which side your bread is buttered

know where your advantage lies.
See also: bread, butter, know, on, side