My suggestion is make sure you READ the scenario. Don't skim over it quickly, don't stare at the strip in front of you, do what you'd do on a real call with a real patient. You look at your patient as you are walking in. What's your first impression? That's what the scenario will provide you with. If you see the 80 y/o female weak, dizzy, with a SpO2 of 88%, B/p of 90/60 who is pale, cool, and diaphoretic, then you look at the strip and see a slow rhythm you can immediately discount almost half of the rhythms you know, and focus on identifying the rhythm and providing the treatment.
By reading it thoroughly you will also catch anything buried in the middle of the scenario...such as 33 y/o male found stabbed in a bar, he's warm, dry, pulseless, apneic, oh yeah...PEA
Lastly...take a few deep breaths...if you're hypoxic, you're patient will be too!
Good Luck and study hard