There's not one best way to play FM. But the beauty of this game is its infinite possibilities. One guy will play the team he supports and try to win it all. Other will start unemployed and write his own story.
I personally always start with an idea for that story. Say, my "dream" is to win the Bundesliga, the top league where football is still more important than money and TV rights. But starting the save there is a bit too easy and boring for me. So I pick one of the sorrounding leagues, where I can have success and then hopefully jump ship to Germany. It could be Austria, Poland, Hungary, and so on.
Another idea is to manage Real Madrid, the greatest club in the world. So I idealize a possible path, say starting young in the lower spanish leagues, maybe try to reach Getafe or some of the satelites and so on.