There can be several reasons for your bird to bite. Before you can figure out what to do about it, it may help if you can figure out why he is doing this. See A Biting Bird - Why Does My Bird Bite Me?
Learn to watch your bird. Most birds give some kind of warning – eyes dilating, fluffed feathers or some other way – to let you know that a bite is coming. If you can recognize the signs, you can avoid a bite by stopping what you are doing.
Sometimes, birds want to be left alone (just like people do sometimes) and unless it's an emergency, you should learn to leave him alone at these times.
If your bird is out with you and wants to go back to his cage, he might have learned that this will happen if he bites you. Teach him another way to ask to go back to the cage, by saying the words "back to the cage" or "back home" every time you put him back. If your bird is a talking bird, he will learn to tell you that he wants to go back to the cage instead of biting. Once your bird has learned to ask to go back to the cage, please return him there when he wants to go.
Think about the situations where your bird bites and avoid these situations.
If your bird sits on your shoulder and bites you every time your child or your husband comes near – don't have your bird on your shoulder when anyone is apt to come near you.
If your bird bites you when you put your hand in the cage to pick him up – don't put your hand in the cage to pick him up. Teach him to step onto a stick instead or wait for him to come out of the cage on his own before asking him to step up.
You may have to towel him to take him out of the cage if he does not step up on your hand or a stick. After you have towelled him a couple of times, you could ask him to step up or tell him that you will use the towel if he does not step up. Our birds understand a lot of what we say and if you show him the towel in one hand and the offer of the other hand, many birds will choose to step up on the hand. Do not get angry if he does not step up. Just quietly, firmly and gently towel him and remove him from the cage.
If your bird bites you, do not react. It may be difficult with blood dripping – but just say "no" and put him down on a stand or on his cage before heading for the band aids.
Basically, instead of teaching your bird not to bite, you are teaching yourself to avoid being bitten.
Here are two good books on bird behaviour that you may wish to check out from Amazon.com or Amazon.ca