To avoid the question:" Do you understand?", I think we should have an overall view of our class.When teaching, you need to make eye contact with your students because you should enforce them to join with your explanation.It has been said: "Eyes are the windows of the soul." If you feel there is something suspicion of wrong in their faces, especially in their eyes, you have to ask them at once by implicit questions about understanding of your teaching.These questions may be W-questions or interview with yes- no questions. It depends on the situation of your class.
For communicative approach method,"Simon says" game, an activity of TPR( total physical response) could help us easily to find who doesn't understand our lesson immediately in checking comprehension step. Besides, there are a lot of other techniques for checking your students instead of asking them:"Do you understand?":Matching pictures, True-false statement, Multiple choice,Ordering statements, Mapped-dialogue, Gap-fill ,Retelling, Jumbled titles,Questions basing on these cues or answers etc....
One thing I like most is "Slap the board" game. I divide the class into groups. The weakest students will have the chance to join in the competition. Everyone will be interesting in learning because it's very easy to slap the board. There is no mistake at all when they don't write anything. However, this technique will make a lot of noises and the headmaster is always against these business noises because its ravage on speaceful atmosphere of some lecturer's surrounding classes.
In conclusion,we should ask our students at the end of every part of the lesson and also after a difficult concept with some implicit questions which appropriate to all kinds of students; the cleverest, the normal and the weakest students.If you use communicative approach method, all of its techniques contain a variety of questions which are suitable with all kinds of students.