Remember that the test is mostly clinical based - there will be alot of clinical 
questions - i.e "If a patient has this presentation of lower arterial disease, 
what symptoms and ABI's will he have?" There are also lots of hemodynamics 
questions. The RVT does not have as much duplex as you would think - at least in 
the past it hasn't. So if you do strictly duplex - you need to study the 
indirect testing considerably more.
You are allowed to mark in the book. When answering the questions, check off the 
answers you know are not correct. Label images, do math work in the margins (no 
calculators allowed). These things help you keep methodical and focused when 
answering the questions.

Study, study, study. Drill, drill and drill some more. Good luck.
Scott Miller, RVT, RDCS, RDMS