Why? Wouldn't the "proper" or "best" way of configuring all these things be pretty much the same for everyone? Why could this just not be a receipe: do all these things, in this order, etc.
Example: good practice is to reject (or at least defer) an email if the sending server is not listed in the domain's SPF record. But lots of people are sending email "on behalf" of gmail without even knowing it (when their mail-server forwards a gmail-message to another address, and this address never receives it).
There are tons of little gotchas like this that you need to look into :((