Lunging is a very touchie feelie thing. Much depends on why you are working the animal off the ground rather than in the saddle. I have reached the stage with my mare where she follows my body position relative to her and the position of my hands. She will now circle at the walk and she will whoa and stand for a couple of minutes. Then we usually move on to walking in hand on a loose rein - starting, stopping, turning etc.
The lead rein/linge line is presently connected to the ring on a mild snaffle fitted to a bridle and any pressure on the line must be minimal. The idea is to communicate not restrict.
Originally we started out lungeing with the pessoas, the surcingle, the bridle and a long whip, each piece of which I steadily discarded. All I use nowadays is the lead line and the bridle - but we are going to start using a cavesson fitted with nose rings soon rather than the bit. Effectively then I shall have little breaking power other than to be able to turn her head, use my voice and give a slight tug of resistance on the nose rings to stop her should she ever freak out. The Olympic sized arena has no fencing although it is raised off the ground. So I shall have to be sure she is in the mood to 'play' with me.
In any session once she has warmed up by circling and been given a little physical work out at trot, extended trot and maybe even canter, I start to lead her on a short loose line when I am relying on her to follow my direction of walk and the slightest of cues from pressure given through the lead line.
But then comes the big question - what am I ultimately aiming to get from her?
In my case it is getting her to follow me 'off lead' ie walk, stop, stand, walk turn. We play games together - I try to vary the sequence a little every session. Maybe one day I'll try backing her up - off the lead line.
To me the important thing with lunging is that she can see me and I can communicate with her thru down thru the line, by the tone of voice, by the relative position of my body and by my hands.
Of late there have been a couple of sessions when I now realise she was in pain thru ulcers (another story). On those days she wasn't listening to me, so what I could achieve was restricted, so I asked her for less.
When setting up the session, I ask myself what are we going to do today? Then I modify my plans according to her mood once I have her working.
Any aggression, irritability, anger or impatience on my part - for whatever reason- is absolutely counter productive.
All I have available to 'direct' her is 'voice' and the subtle pressure on the line but it has taken some time to get to this stage.