Low blood alcohol level is a good thing. Hitting stuff while taking the test is bad.
I've known guys that have ignored those two. One guy showed up for his test (at 16 years old) after having a beer. Another hit a guy on a bike during the test. Need I mention that they both failed instantly.
It's been about 10 years since I took my test (in California), but I'd say just make sure you practice a lot, so it's natural to you, not forced. Other than that, it's not difficult. Use your signals, stay between the lines (unless instructed otherwise), and be aware of the cars around you. If an emergency vehicle comes up with it's lights flashing, get out of the way - preferably to the right side of the road. If you don't, I'm pretty sure it's an instant fail in some states.
"Guns Kill People."
If that's true, then I guess it's my pencil that makes spelling mistakes.