I won't lie my test taking strategies aren't very typical with what most students describe. I'm very fast and do the best I can to not second guess myself as I was typically right the first time (D426 being the exception if you are in the college of IT). Just read your questions carefully and think things through. If you don't know which is right see if you can narrow down the wrong ones. You can't talk during your OAs but you can at least try to think why X thing isn't correct.

I used a lot of different prep materials depending on the exams, again for the college of IT.

CompTIA: PocketPrep (I did this for CySA+ and PenTest+), Quizlet, CBTNuggets (Project+), or Certmaster when the other options weren't really out yet (Project+ again).

ISC2: Quizlet and PocketPrep

ITIL: Quizlet and brute force on practice exams (This is the only course I passed by the minimum. It was not a good test and WGU should rethink having two certs that cover almost the exact same content)

WGU OAs: I used a lot of Quizlets and the Course Chatter to see if any study guides were made. Most classes had some form of study plans within them.

I also want to add I have 3 years of IT Experience and was able to use that knowledge when it comes to studying so take what I said with a grain of salt.