Read up through combination vehicles at least in the handbook. The practice tests on this site are great. I read the handbook and did the practice tests (and reviewed my wrong answers to commit the right ones to memory!!!) for general knowledge, air brakes, and combination vehicles until I aced the practice tests. I got my permit last week with only three days to study around the full-time task of taking care of my two year old and two month old kids myself, lol. You should be fine.
Add a TWIC Card, Hazmat and Tanker to your list after you get past the basics. I find that having these makes you golden. Good luck.
I know you weren't asking this question to me but you can go here: http://www.twicinformation.com/twicinfo/
There are some really good practice tests online of which are almost the same as the real test. If you do good on those you should be fine. It really isn't too hard. Maybe the airbrakes and log section will be the hardest. Definitely not rocket science though! Another very good source of study materials is your Motor Carrier Road Atlas. There is a wealth of information in there! Everything from logs to pretrips etc... Of course you can also use this to practice your trip planning. This will be one of your biggest keys to success! The better you can trip plan the more money you will make and the happier your dispatcher will be.
