Accidental biting:
Don't get them too wound up. When the bite pressure starts getting harder stop the game and calm them down before continuing...
AND FOR GOD SAKES BITE PRESSURE TRAIN YOUR BIRDS!!! THEY DON'T ALWAYS KNOW THEIR OWN STRENGTH. THEY SHOULD PINCH, NOT BITE!
How exactly is this achieved?
I can tell you my methods. For Bixby, I always used the "wobble technique" if he was on my arm when it happened. Basically, as soon as his beak pressure passed an acceptable amount of pressure, I would wobble my arm enough to threaten his balance (though not so much as to actually make him fall. Bit of a tightrope, that.) while telling him "No", or warningly saying, "Nice", in a stern, even voice.
Eventually, he came to associate heavier beak pressure with the unpleasant sensation of a loss of balance. He also came to associate the word "no" with the same.
And if he actually latched on while on a perch or something other than my arm, I never advocated the method of non-reaction. I always calmly used my other hand to grip his beak and gently leverage my finger/hand/arm out from his beak while telling him no.
After the first warning, a repeated offense always got him put on time out. And when on time out, I would turn my back and ignore him for between 5 and 10 minutes. This was most effective when I remained in his line of sight, pointedly ignoring him, rather than in another room.
Bixby now rarely nips, and never bites.
Now, since getting Maya, I've had to amend my method somewhat. She has never given me anything but the gentlest pressure, but she has drawn blood from my wife. So I gave my wife these same pointers and learned, much to my surprise, that the wobble portion of the techniques that worked so well with Bixby didn't work with Maya at all! In fact, they would send her into a rage fueled biting frenzy that would force me to intervene.
See, her balance and grip strength is just superior to Bixby's. So all wobbling did was further annoy her. So we've had to adapt. Timeouts are now her principal deterrent. And we make sure to use it consistently. It's still a work in progress, and she sometimes holds a grudge against my wife after the timeout, but overall things are improving between them. (Especially now that I always play the bad guy who puts her on timeout, and she plays the good guy, rescuing her from the timeout.)
Don't know if any of that helps, but figured I'd share.