You don't have to read all of Dale Ralph Davis' six Old Testament commentaries (although you'd enjoy them, I'm sure). In 2006 Davis produced a book called The Word Became Fresh: How to Preach from Old Testament Narrative Texts. While this book focuses on preaching the OT, it also gives a clear outline of Davis' approach to studying the OT, and I believe you'd be hard pressed to find a better overview of OT Bible study anywhere. The book is only 154 pages long, it's easy to read, but it doesn't lack depth. Check it out.