The links below are for the VCP6-DCV certification.
I'll be focusing on the 2V0-621 exam, not so much on the 2V0-620. There is also the 2V0-621D (delta exam) which is now very similar to 2V0-621 but shorter and more focused on v6 differences - however, the same strategy applies. (Historical nugget, here's what the delta exam was like before).
Always start by reading the Official blueprint and documentation. Below is what I consider a fail-safe strategy that will take a lot of time but should leave you in excellent domain of the VCP6-DCV topics.
First, the warm-up. This is a phenomenal blog post by Daniel Mizrahi - especially if you are completely new:
http://blogs.vmware.com/tam/2016/02/prepare-vcp6-exam.html
In general I recommend following Daniel's blog post as much as you can, but in the case where you don't need to take a course and you don't want to spend any more money than the exam fees, you would do only these two as a warm-up:
[free] VMware vSphere: What’s New [V6] Fundamentals e-course (1.5 hours)
** Ariel review. This is a great introduction to the v6 changes. In particular, a hidden easter egg is that this intro course has an exam at the end! I thought the course was just covering changes and somewhat high-level, but once I got to the questions I realized two important things:
1. THIS IS A MEMORIZATION EXAM! Remembering if something 60, 62, 64 or 68 MATTERS!
2. There are many changes in vSphere 6 and this exam is very large.
[free] vSphere Foundations (2V0-620) Practice Exam (45 minutes) this should be an "easy" practice exam for you - anything covered in foundation can be covered in the actual exam so if you are not getting points here, your may want to revisit the foundation topics.
Second, I recommend reading the PDF documents stated in the blueprint. This can be a daunting task, since this is the actual product documentation and not everything in each document (some are very large) applies to the exam objectives. However, this is free. If you aren't clear on a subject, the best way to learn it is practicing it in your home lab or the VMware hands on labs.
I will leave a table here as I study with a column of the PDF documents and specific page numbers per section as I study each of the PDFs mentioned in the blueprint. Please note the PDF documents can change without notice and the page numbers may not be accurate in the future. Also, take my advice with a grain of salt as VMware leaves this open ended and I may make a mistake.
Note - I don't recommend skipping this part; it's always best to read the official documentation as instructed in the blueprint. If you are very time constrained you would skip to the next sections, at your own risk!
Third, you study the official study guide. As of this moment, it isn't released (tentative May 2016). However, you can start reading the "rough cuts" version with a paid Safari Books Online subscription (free 10 day trial). If you have that subscription you get the digital form of VMware press books when they are released.
Another excellent book you can use is Mastering VMware vSphere 6 by Nick Marshall. This is an IT administrator's book mainly, but the certification topics are mostly covered.
I will leave a table here as I study with a column of the topics indicating which of this book's pages that cover that specific topic. Again, take my advice with a grain of salt as I may make a mistake.
At this moment I would schedule the exam maybe three weeks in advance since you've done the main preparation and are going to enter review mode. Read below and value how much time you will need.
Fourth, enter review mode. There's video, blog post and online study groups formats:
>Video, paid and free options:
[paid] VMware's own Learning Zone / Certification Exam Prep videos. I have not heard much users or reviews of these to recommend either way.
[paid] Pluralsight has a VCP6-DCV series. For past exams in version 5, I found the videos to be very useful and the player easy to use - perfect for watching while telecommuting, relaxing or at the gym.
I will post the link to each video in the order he covers the sections.
[free] vBrownBag has a VCP6-DCV track. These are popular community-driven "lunch and learn" type recordings.
>Blog posts, all free thanks to the vCommunity. These are the best ones imho:
http://www.vladan.fr/vcp6-dcv/ by @vladan
http://www.virtuallanger.com/2015/08/25/the-unofficial-official-vcp6-dcv-study-guide/ by @jaslanger and @joshcoen
http://vwannabe.com/vmware/vcp6-dcv-study-guide/ by @dadowistef
>Online study groups, all free
VMware communities - VCP certification excellent place to get questions answered, moderated by VMware
Google+ VCP6-DCV community Excellent place to talk with others who are studying and especially to discuss and get opinions and advice (within NDA).
Fifth, practice tests. Right now this is the only exam I've found but if I find others I'll add them here.
[free] VCP6-DCV Delta (2V0-621D) Practice Exam (45 minutes) this is the same practice exam for 2V0-621 and 2V0-621D since the blueprints are about the same now. You should at this moment find this exam easy, and if you miss any points you need to go review that section again.
Sixth, take the exam. Remember to:
arrive early
get a good night's sleep
have some long-acting carbohydrates such as oatmeal before
be mindful of time management
flag questions you find difficult for later review
use elimination when you aren't completely sure you have the right answer
Good luck! I hope you pass with a maximum score, and more importantly, become a much better vSphere administrator. Feel free to leave me your comments below and reach out on twitter @arielsanchezmor for any comments, questions, or to brag about your perfect score!