The phrase "make it up as goes along" can be used to describe someone who is improvising or making decisions without a clear plan. Some synonyms for this phrase include "winging it," "improvising on the spot," "playing it by ear," and "flying by the seat of one's pants." Other related phrases include "ad-libbing," "making it up on the fly," "freestyling," and "making it up as one goes." These phrases all convey a sense of spontaneity and improvisation, suggesting that the person is relying on their instincts and creativity to navigate a situation without a fixed plan.