I think the most important thing you need to realized before attempting a Certification examination is the fact that you need to know how the program works. That is you need to understand how the information is processed with each statement you type when the program is submitted and how each character changes what the program does. If you realize that, because this could be considered an exact science, there is no other possible outcome for each code.
Personally, just 2 days ago, on March 8th, 2018 I just obtained my third SAS certification. I succeeded on my first attempt in all 3 of them.
I have a BASE, ADVANCED and BUSINESS ANALYST: Regression and Modelling Certifications.
For the first two, I simply studied the Certification Prep Books published by SAS (For the Base Programmer is all you need, for the Advanced there are about 3 topics you'll need to find elsewhere), the other certification is a different story most people might not be interested in.
Make sure you understand how the program works, make sure you understand its logic, If you do, you will be fine.
PS: I am a Medical Doctor with a Master's in Public Health, later in the year I will begin my PhD in Epidemiology with absolutely an background in computer programming at all, this is the first programming language that I have learned and did it from scratch without taking any classes all by myself from reading the books.
Links to my profiles:
https://www.youracclaim.com/user/fermd
https://www.linkedin.com/in/fermd/