looks out for number one

Verb

look out for number one (third-person singular simple present looks out for number one, present participle looking out for number one, simple past and past participle looked out for number one)

1. (idiomatic) To act in one's own interests; to act in a manner advantageous primarily to oneself.
   • S.—Ah—get out. Look out for number one—that's my doctrine; and let others do the same;—and if they don't, why, the flats must be contented with being gulled—that's all. It is n't my look-out, if a man does n't know enough, or does n't think enough, or is n't careful enough: if I can shave him a...1833, George Washington Light, “Sketches of Character: A Schemer”, in The Essayist: A Young Men's Magazine, volume 1, G.W. Light & Company, page 318