To create a signature go to your profile and add info into the box labeled signature. Be sure to save your profile. And then all your posts will now display your signature.
There is a character limit to the signature so long signatures could be cut short.
As for a template, helpful info to ones story is used like if you are the betrayed or wayward. Some will add the dates of d-day. If separating or divorcing, most will add that status as advice to those situations could result in different advice than one looking to reconcile.
People will often state if they have kids and ages as that can lead to helpful tips and experiences from other that have kids of similar ages.