Depending on the type and sophistication of the FD, sometimes it is best flown when you make the bars come to you, instead of you going to the bars.
In more sophisticated ones, following the bar "blindly" is usually good enough in most circumstances.
Practice flying with FDs ON is advisable. You may one day lose AP but have FD available, along with other failures (say dual hydraulic or whatever) and if you never practice that, you won't do it as well as you could.
As for low experienced pilots, it is a good practice, to learn how to correctly fly the FD, smoothly and without rushing (not confusing a bar suddenly going fully right with a "quickly bank right" command, for instance).
If you want them to learn to look behing the bars, though, they will have to practice no FD hand flying.