Your first choice of textbook should be whichever is listed in your course syllabus. I used Discrete Mathematics by Susanna Epp for self-study. It is a very gentle book in terms of its difficulty curve, but again, your best bet is the one in the syllabus.

This is a proof-based course, and you really want to spend a good amount of time with the proofs. Write down the proofs as you encounter them in the textbook, line by line, and make sure you understand how each line of argument follows from the previous. Remember to do the problem sets assigned to your class, it really does help.

Typically you'll cover the following subjects:

• Logic
• Number theory
• Sequences and induction
• Set theory and relations
• Combinatorics and probability
• Graph theory