take a leaf out of someone's book

To do something in the way someone else would do it; to behave or act like someone else. I think I'm going to take a leaf out of your book and start going for a run first thing in the morning.

Imitate or follow someone's example, as in Harriet took a leaf out of her mother's book and began to keep track of how much money she was spending on food . This idiom alludes to tearing a page from a book. [c. 1800]

COMMON If you take a leaf out of someone's book or take a leaf from their book, you copy them, usually because they were successful when they acted in that way. Note: The `leaf' in the last two expressions is a page of a book. Hollywood celebs should take a leaf out of Michael Douglas's book and make sure their websites are interesting and attractive. You're working too hard. Take a leaf from my book and relax!

To imitate someone; to follow someone’s example. Literally, this expression alludes to either vandalism (tearing a page from a book) or plagiarism (copying someone else’s work). The figurative use of the term, which dates from about 1800, is much less nefarious. B. H. Malkin used it in his translation of Gil Blas (1809), “I took a leaf out of their book,” meaning simply, “I imitated them,” or “I followed their example.”