Anne-Marie Edde's biography of Saladin (called Saladin) goes into contemporary life in the Middle East in pretty thorough detail. It obviously leans more towards the Muslim side of things than the Crusader States but does include some information on the latter. It also has a huge 'further reading' section at the back if you want to go into more specific detail.

The only thing I'd warn you about the book is you need to have a decent grasp of general Crusading history before you read it. Edde definitely didn't write an introductory text so she expects you to have some familiarity with the broad strokes of Saladin's career before you read it. I recommend Thomas Asbridge's The Crusades as a good starting book before moving on to Edde's, if you haven't already read some Crusades history.

As /u/Valkine has mentioned, having at least a decent grasp of the history of the Crusades will be helpful before tackling any work that would cover "the life in the Crusader states." Most of my Crusades-related books are fairly in-depth (Steven Runciman's trilogy on the subject, Jean Richard's textbook, etc.), so I'd talk with others about figuring a good baseline history book to start with.

That being said, I do have a book in my collection that fits your actual question perfectly: Andrew Jotischky's Crusading and the Crusader States. While it does go over the actual history of the Crusader States, it does have chapters focusing on life within the Levant, as well as socio-political aspects of society at the time. In general, this book is less concerned with the "who and when" and more in-depth about the "why and how." It's mostly going to cover time between the first and third Crusade, but it should give you a good answer to what you're looking for. It is very much a textbook, however, and reads as such.

Try 'The Crusades Through Arab Eyes' by Amin Maalouf. It's a while since I read it so I'm not 100% sure how much it covers everyday life but it provides a valuable contrast to purely western / christion views.