Rely on simulator exercises. Ask yourself the "why" behind whatever you are doing. Read and understand the application well. Before you even think of appearing for any CIS exam or certification (in general), you should be able to confidently explain every functionality on the application and when should what be used and be able to talk about the trade on and offs between various functionalities. Because, in ServiceNow and in general, there are many ways to solve a problem statement, but only one is the best way. "Blueprint" is your bible. Follow it!
