Chop,
Like CHG already stated, this is a well worn path, many have travelled it and there is plenty to chew on in the archives.
I took the week long AWS sponsored prep course to help prepare myself for the exam, however many have passed the CWI exam by self studying. Like I've said many times, the prep course was a great help to me in that there were questions asked on the exam about materials that I've never had to deal with in the 20 years I've been in Structural Steel fabrication. There are materials for sale in the For Sale forum to help with your self study if you choose that path.
Good Luck on your exam, and if you have any specific questions don't hesitate to ask.
John Wright