My best session?

I think it is a common thing :). For me , contracting with the aneros inserted usually leads to the feelings you describe, and with some practice (and sometimes visual stimulation, ie porn) it leads to a handsfree wet orgasm. I haven't had a dry o up to now. The rocking technique sounds interesting, May be I'll try it sometime.
Regarding contractions: for me the best position is to lay on my back with my legs bend (feet flat on the bed). I contract irregularly, sometimes very lightly and sometimes very strong. This usually leads to a strong flow of precum (sometimes I manage to push out a few drops of precum with every contraction, in a prostate- milking kind of way) , pleasurable feelings and eventually a handsfree orgasm. Nowadays I try to edge with this technique, in pursuit of something more than a wet orgasm. (No results yet).

Everyone has different ways of enjoying their Aneros toys. This is not a dildo; you need to be careful not to ride too hard as you may bruise your prostate. Enjoy every moment!

Remember the Aneros prostate massagers generally are not masturbation aids. I would suggest 'taking it easy' with your prostate as GGringo mentioned.