It's not that easy. It depends on the ration of fermentable to unfermentable sugar in your batch. If you are asking how many to shoot for in a style of beer the style guidelines have this. However there is no way to tell you what your porter (lager, stout, etc.) should have for fg without seeing the actual recipe and procedure. Some types of beer will finish in the 1.020s and others under 1.010.
"So you say you just brewed your first batch of beer. Welcome to the obsession." --me, to every first time brewer I ever meet.