This is some geat tips on how to tame your tegu. Let me first say, put yourself in your tegu's position. He is small and you are very big. Big things eat small things. So in his mind he is thinking you want to eat him. To start with, you must build trust with your lizard.
Here is some helpful hints: first off, the most important thing that people do wrong, is disturbing them when they are in their hide, never do this, this is their place of safety, that is one sure way to lose trust with your tegu. Next never (man handle) them, they seem to respond better if you are gentle. It is not going to happen over night. And just try to stay calm around him. If he thinks you are going to hurt him he will go into the fight or flight response. So just take your time, and he will realize you are not a threat and calm down.
Keep this in the back of your mind. In the wild these little guys are prey, so when you handle him, remember this. He will come to know you as a friend and not a foe. If you are gentle and slow when handling them, they will feel more comfortable, and respond better when they are handled. It is very important to remember tegus will not respond to human contact if they are handled with the thought of making them do what you want. Tegus are very curious; it is best to use this to your advantage when getting them to become calm pets. The more you fight with them, the more they will fight back. I use a method I refer to as ignoring them to tame them. I have used this many times with great success, this has also worked on the older untamed adults. Letting them come to you can use this method. I have walk in enclosures, I use this by spending time inside them working or reading books. I just do not act like the tegu is even in there, they see me, but I am not trying to invade their space. They will learn that I am no threat and come over to investigate me, it is like the old saying: (curiosity kills the cat). They find out that I am not a predator looking for a meal, nor any kind of threat to them. They will come to learn I am a friend and not a foe. You can use this same method in your home, you need to make sure there is nothing that you tegu can harm itself on, this needs to be a tegu safe area. When your tegu comes to you to investigate you, do not make sudden moves or try to grab him. Just reach down and pet him the first few times, I would not even try to pick him up the first few times. When you do pick him up, think of them as your puppy, when you pick him up, do not grab him behind the neck or around the belly, just reach under him. Hold him with a light grip. Also, the first few times you do pick him up, do not raise him high off the floor, give him a chance to move from your hands and he will learn he is not restrained. You want him to choose to have your contact. He will never learn this if he is man handled; he will also remember the fights. Tegus are the same as a puppy, they don't like to be grabbed either. Instead reach under them with a loose hand and be gentle. Also when handling them. Let them move through your loose hands, just keep putting one hand in front of the other until he calms down and stops moving. Just remember, the more you grab them and try to restrict them, or chase them, the longer it will take for him to trust you and become tame. The more interaction you have with him, the better. But this does not mean the contact you are making with him is making him do what you want, remember force will be responded to with fight of flight. Just try to handle him with a very slow hand, in a calm manner.
Another point that I want to make is tegus can become very food aggressive. They can and will associate you with food. They will bite the hand that feeds them; this is not done in an aggressive manner. My advice to this is never feed them in their cage. Never let them see you feed them. The best way to cure this problem is to not feed them in their cage. Put the food in a separate cage, and then take the tegu from his cage to the food. This helps in many ways. You are putting him with the food, not bringing the food to him. This keeps the food aggression to a minimum. Also by doing this, you are handling him twice a day, once to take him to the food, and another when you return him to his cage. It also helps to keep from getting impactions. If you keep him on sub straights, and remove him to feed him, then you could feed him on newspaper. Then there would never be a chance for him to ingest the sub straights. Also, never feed live mice and rats, this only increases the strong instincts to chase something that moves. I will also add, dead rodents do not bite, bites from these animals can cause damage to your tegus.