Know who you’re looking for. You should understand the objectives of the role the candidate is interviewing for. That way you can ask questions that lead them to talk about how they’ll accomplish those objectives.
Ask purposeful questions. The questions you ask should help determine if the candidate can accomplish the role’s objectives. Ask pointed questions that get you the answers you need and open-ended questions that let the candidate make their pitch. Don’t wing it or ask too many cliché interview questions.