Well, first off I always made sure to read the entire lab before starting working. This was the first advice that was given to me when I started studying. Also, it helped me out immensely to draw out anything that I did not fully understand in my head.
I also had/took time to look over things before the end of the test to correct any errors that I made. This was mainly for the things that I could not verify by some means. Also, take the time to reboot your routers after configuring routing. There are some things that can be configured automatically that can enable things to work when you may not have it truly configured correctly. Also, it may stabilize things that are not working as you would think.
Finally, you will want to wear a long sleeve shirt and maybe bring ear plugs if you find it hard to concentrate with others working around you. Also, do not plan on sleeping much the night before the test and the night after. I know that I was not able to sleep much either night.