Background: Currently I know the most basic notions of category theory, as covered by the first chapter of Jacobson's Basic Algebra II or the last chapter of Hungerford's Algebra, up to Yoneda's lemma and adjoint functors. (However, I think I need to learn these again.)
Motivation: I'd like to study Category Theory to smooth the way for Homological Algebra, so that I'll be able to read texts such as Weibel's An Introduction to Homological Algebra (tried to read it, but got stuck due to lack of familiarity with abstract abelian categories). However, this motivation is not very much a restriction on what I want to learn; I just feel that my knowledge of Category Theory is insufficient. Therefore I'd like to read a book entirely devoted to Category Theory.
I have went through the first pages of Mac Lane's classic Categories for the Working Mathematician and find it very readable. Is Mac Lane's book suitable for my purpose? If not, are there other books on Category Theory that you may recommend? (I'd like to study categories in a systematic manner, so books entirely devoted to it are preferred.)
If I choose Mac Lane's book, do I need to read from cover to cover? What are the logical interdependence of the chapters? And most importantly, which parts of the book do I need to read in order to prepare for Homological Algebra?
Thanks for any advice!