Here's a couple 'tricks' they used when I took the test.
1. There will be 3-4 questions about a similar situation. Let's say they're concentrating on Rigid Metallic Conduit. You'll get several questions in a row about it.
What is the minimum bend radius of 2" Rigid Metallic Conduit?
Which of the following locations is Rigid Metallic Conduit not allowed?
Rigid Metallic Conduit shall beclearly and durably marked every ___ feet.
What is the maximum distance between supports for 1" Rigid Nonmetallic Conduit?
Now, if you weren't paying close attention, you would get that last question wrong. Go back a look closer if you didn't catch it.
2. I remember well the last two calculation questions. The first showed a diagram of a feeder with 3 motors tapped off it.... a 3-ph 5hp, a 3-ph 10hp, and a 3-ph 20hp motor. Calculate the minimum feeder size. (I don't remember the actual sizes, I'm just using these numbers for this example...)
The next page had the same diagram, but added 21kW of lighting to the feeder. So you think it's easy.... just add 25% to 21000, go back so far in your calculations, plug the number in and refigure, right? What you didn't see was the 3-ph motor on the second diagram is single-phase, not 3-phase. THAT is enough to change the wire size.....
And the one question that everyone got on their test when I took it is:
You are wiring a 5,000 sq. ft. custom home, and the owner wants to add 19 more receptacles throughout the house. What is the effect on the service? The answer is zero. Not 180va per recep, not 180va per strap, not 180va anything.
Other tricks:
If you cannot locate an answer in the codebook, move on.... don't spend too much time dwelling on one question. The clock is ticking. If you have time at the end, come back to it. If you are simply and totally stumped, it's multiple guess and you've got a 25% chance of getting it right. You may also stumble across the answer while searching for another question.
With calculation questions, look at the examples in the back.... sometimes you may get lucky and your question is identical to an example. It may be the same question, but the numbers are different. Punch in your numbers in the example, and you've saved a ton of time.