I think that when preparing guiding questions for a lesson, a teacher should keep in mind the beginning and the end of her lesson.She should develop questions that will introduce the topic to the students, and at the same time demonstrate what she wants them to be able to do at the end of the lesson. An example of this might be "What is pollution and what can we do to prevent it?"
Good guiding questions should be open-ended so that students have to use critical thinking skills to answer them. In order to answer the guiding questions, students should be able to collaborate with each other and use a variety of resources. This way, they already have an good understanding of the lesson. After the questions have been answered, then the teacher can guide them through the rest, instead of lecturing. In addition, good guiding questions should relate the content to the lesson to the real world and to students' individual interests.
