http://www.redhat.com/certification/rhct/prep_guide/The study guide above from Red Hat tells you exactly what you need to know to pass the exam. You may not see everything on the list, but I promise you if you know everything on the list and are comfortable configuring them, you will do just fine on the test.
My best advice to you is trust your gut and take your time. You will hear that the Red Hat tests don't give you enough time in order to complete everything. That isn't true. You have enough time as long as you take your time and don't skip over minute details. The minute details are what will kill you if you don't pay attention. You'll end up spending 20-30 minutes chasing your tail on something that should have taken you 2 minutes to fix if you aren't careful.
Good luck!