I'm currently using this book and think it's well worth the $15 I paid for it. Otherwise there are a number of frequency lists you can use.
https://www.amazon.com/Big-Red-Book-Spanish-Vocabulary/dp/0071447253
I wish they had kept this series going with French, Italian....
http://www.amazon.com/The-Big-Book-Spanish-Vocabulary/dp/0071447253
i recommend this book, i currently do not have my copy on my persons or else i would try to explain more, but it helps me everyday in class! there is also a verb edition