Our church is in the middle of a 4 week sermon series in the Gospel of John. Here are my recommendations for studying the book for yourself:
Bible Dictionary:
The Holman Illustrated Bible Dictionary is my go-to Bible dictionary (I have 4-5). John goes out of his way to explain many cultural/geographical details to the uninitiated reader. It is, however, helpful to have a handy reference for terms, cultural practices, and geography.