Good resources (book or otherwise) to learn/study basic Combinatorics
Solution 1:
IMO there are two great references at two different levels. The first is Brualdi. This book is awesome. It is super clear, super straightfoward, and very readable by yourself.
The second is much more advanced, but even better! It is Aigner's GTM on the subject. This book is fairly advanced, but rarely have I seen such a beautiful exposition of any mathematical subject. His proofs are impressively elegant, and his exercises are very interesting.
I hope this helps.