I think the little letter to Titus is in many ways a discourse on church health. People today often overlook this letter, but Luther said of it, "This is a short epistle, but a model of Christian doctrine, in which is comprehended in a masterful way all that is necessary for a Christian to know and to live." Here is a link to an article I wrote seeking to expound the overall message of this letter. I argue that the structure of the letter shows that the letter details four necessary elements of church health: Proper Leadership, Proper Response to Error (moral and doctrinal), Proper Living, and Proper Understanding of the Gospel. A pdf version of the article can be found here.
I have often used this (in oral presentation) with churches in interim periods or other times of self-evaluation.