With the littles, biting will happen once in awhile...usually when they're tired, or when we have to handle them when they're not in the mood for it. We tend to use a "hands off" policy with them...only physically interacting with them if they want that to occur...or goodness knows, if there is an emergency.
People have commented on how little we physically interact with our birds...well, my wife and I consider them to have the right to be birds...if they don't want to interact with us...fine. We're always here to be near, if they choose. I think that's why we got along with our IRN (a known non-cuddly species) for so long. Titan knew we weren't going to force anything on him he didn't want...so when he wanted something from us, he'd come to us.
Igor Tiel is also like that...he'll fly over to you when he wants scritches or some such...as soon as he's had enough, he'll fly away.
Getting back to biting...Milton has gotten me many times. The thing about Milty is that he'll show you- in body language and verbally- that you may be heading for a bite if you don't back off. He's a very good bird in that way...and if you tell him that, he'll agree with you.
The other circumstance where Milty will bite is if he gets overexcited...a rather common thing in 'toos. He gets excited in his play...and when he watches "The Price Is Right." These are times I know to give him a LOT of space to expend his excitement and energy.