In a SharePoint list I want an auto number column that as I add to the list gets incremented. How best can I go about this?
You can't add a new unique auto-generated ID to a SharePoint list, but there already is one there! If you edit the "All Items" view you will see a list of columns that do not have the display option checked.
There are quite a few of these columns that exist but that are never displayed, like "Created By" and "Created". These fields are used within SharePoint, but they are not displayed by default so as not to clutter up the display. You can't edit these fields, but you can display them to the user. if you check the "Display" box beside the ID field you will get a unique and auto-generated ID field displayed in your list.
Check out: Unique ID in SharePoint list