The phrase "blunder up on" implies making a mistake or error. Its antonyms, however, convey a sense of caution, deliberation, and precision. These include phrases such as "plan ahead," "think through," "carefully consider," "deliberately choose," and "strategize." By taking a careful and considered approach, one can avoid making blunders and mistakes. Thinking through decisions and carefully weighing options can lead to better outcomes and avoid unnecessary errors. It is essential to choose words and phrases with intention and consideration, especially in situations where even the slightest blunder can have significant consequences.