I would highly recommend Shankar's "Principles of Quantum Mechanics", a book from which I learnt quantum mechanics in 12th grade (no, this says nothing about my abilities, but instead goes to show how fantastically good Shankar is in explaining the principles of quantum mechanics to a high school student interested in self-studying it before college). This, followed by Feynman's Volume III, were my first taste of quantum mechanics before I even started undergraduate studies in physics.