I took a practice test from the following web site before going to the DMV:
http://www.freedmvpracticetests.com/
They give you FREE 20 question DMV practice tests, and additional motor vehicle tips/information. I ended up passing the DMV test the first time I took it. Every other web site I went to either wanted to charge me for a test, or didn't have all the information I needed.
Check it out, hope it helps!
You can access a general DMV practice test, and other helpful information at DMV.ORG - The Unofficial Guide to the DMV.
View this page (http://www.dmv.org/practice-tests.php) to access the general practice test. However, we strongly recommend that you study the driver's manual (http://www.dmv.org/driver-handbook.php) for your state!
Good luck,
-DMV.ORG Support
http://www.humanumbrella.com/2009/03/23/north-carolina-dmv-questions-free/