My favorite law book is Evidence in Action by Justice Pronove. It's funny because I discovered that law book when I was almost out of school, and only a few months before graduation. It's actually not the typical hard-bound and heavy book used in law schools - it's more of a primer and contains less than 300 pages.
What I liked about Evidence in Action is that it has discussed the most important matters about evidence in the simplest way. It's also very helpful on teaching students and new lawyers on how objections are made during litigation.
I know it's both hard and scary to say your very first "Objection, you honor." in court. But reading Evidence in Action has taught me how and when to object. It's a very friendly book and it cost me a little over $10. It's a little book that every law student and lawyer must own.