Templates are well-suited to be put into source control systems such as Git. There are plenty of ARM template examples on GitHub that can be used for your own purposes. The Azure Quickstart repository alone contains a whopping 690 templates, for many different workloads:

All of those templates share the same structure—the template itself (called azuredeploy.json), the parameters that can be passed to the template (called azuredeploy.template.json), and some metadata, with additional information such as the author and the description, in the file metadata.json:

The internal format of a template always looks the same. Whether or not you use certain sections, such as parameters or variables, is completely up to you. Since our ARM templates should be as generic as our DSC configurations, it makes sense to gather variables and parameters from configuration data. This ensures that the work you put into your templates is not wasted, and that the templates can be used as building blocks by other teams:

{
    # Mandatory schema
    "$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
    # Mandatory content version
    "contentVersion": "x.x.x",
    "parameters": { },
    "variables": { },
    "functions": { },
    # Mandatory resources
    "resources": [ ],
    "outputs": { }
}