Whizlabs practice exams were immensely helpful - obviously the questions were different, but the difficulty level, format, and topics covered was spot-on.
To initially learn the concepts I used Linux Academy and had some hands-on experience at my job as a developer. However, this would not have been enough to pass the exam as it was very comprehensive and covered some newer services that were not in the 2018 version of LA (but were in WhizLabs practice exams).
I took all the practice exams and the detailed ones too. One thing to note is that the difficulty level of the real exam was the same as the practice exams, especially how some questions would be easy (like choosing a service to use where there was obviously only right one answer) while some were difficult and required in-depth knowledge of the services.
When you’re doing the real exam, if you have time leftover (which you should have plenty of) I highly recommend going through all the questions again to make sure you didn’t miss anything. A few of the answers I changed because I hadn’t thought through the question enough on the first time.
For what it’s worth, I was scoring about 83% on the Whizlabs practice exams on the first try. You should probably aim a bit higher than that but I was on a time crunch.
Good luck to fellow test takers!