Because I was foolish or bold enough to start studying for VCAP5-DCA and VCAP5-DCD at the same time, what I wrote on my VCAP5-DCA page regarding study guides will also apply to my VCAP5-DCD study.
There are a lot of very good study guides out there, I will sum up the one's I used when studying for my VCAP5-DCD exam. For this exam there isn't much you can do regarding strategy, but you can (or must) follow some sort of time management.
The study guides and books I used to study / prepare for my DCD exam.
VMware vSphere 5.1 Clustering Deepdive (by Duncan Epping and Frank Denneman)
VMware vSphere Design (by Forbes Guthrie, Scott Lowe and Kendrick Coleman)
Both books are great reading material, not only during studying but also as reference guides.
ProfessionalVMware vBrownbag VCAP5-DCD sessions (by Nick Marshall)
VCAP5-DCD study outline ProfessionalVMware (by Cody Bunch)
VCAP-DCD Design tool user interface demoVMware VCAP5-DCD Exam blue print
Regarding strategy / time management, I'm probably not the first to "warn" you that in this exam time is your worst enemy ! Especially since VMware decided to remove the "question flagging" option which made it possible to skip and save a question to answer it later on in the exam.
So the way I handled this, as you might know (or should know) the exam consists of 100 questions which are a mix of multiple choice, drag and drop and design questions. You never know what type of question you are going to get next, but 1 thing you do know is that there will be 6 design questions. VMware states that you will need about 15 minutes to complete each design question, so these should take up to 90 minutes of your total time of 195 minutes. If you are, like me a non-native English speaker you will get a extra 30 minutes which brings the total to 225 minutes. So you roughly have to complete 25 questions per hour if you want to finish all questions within the allowed time.
As you do not know when a design question will be presented you have to write down how many you already did, so you know how many you still have to address. So when your are about half way through your exam time and you had 4 design questions to answer already but only have less then 50 questions answered. You should not panic because you only have 2 design questions left to answer and this should leave enough time to complete the remaining 48 questions.
In short mark every completed design question on your slate and keep an average of 25 questions per hour, this should keep you from running out of time.
Hopefully the above book and study guide tips together with the time management tips will help you to prepare for your exam. Good luck to all pursuing this certification !