You had just graduated from high school?
Usually undergrad QM lecturer uses Griffith's Quantum Mechanics, which I did use in my undergrad time. The way he conveys his idea is not too formal making it suitable for beginner. The early problem QM beginners would most likely encounter is solving Schrödinger equation, a partial differential equation, for simple cases. Therefore a knowledge of solving basic partial differential equation is very recommended. Knowledge of some special functions will also be very helpful. At a certain point, you will also be 'forced' to study linear algebra when you begin to touch the ket notation.