One word: Communication
From the very beginning of any project, I want to be sure that what I am envisioning that the client wants is the same thing the client is envisioning that they want. This is why I will ask the client to spend some time with me explaining, and showing me, what they want, or to present pictures or actual examples of what the client is after.
I can also present some pictures or examples to the client if I feel there is any question as to what the client is after. I have been very successful in understanding what my client are wanting to achieve, and delivering a final result which the client is very satisfied with.