It's all about asking the right guiding questions and offering support at critical junctures. I often see tutors explain an entire problem and solution, then ask the student if he or she understands, and inevitably the student will answer "yes" and they will move on. I look for proof of understanding. For example, if a student struggles with a complex math problem, I will encourage her to take a step back and think about what she already knows that helped her get to this point. Then we work through the problem step by step. Another example could be in critical reading. I'll ask the student to read but pause in certain places to ask questions like, "Why do you think that sentence is there?" or "What does that quote reveal about the character?" Over time, students learn to ask those kinds of reflective questions of themselves, once the technique has been modeled for them.