My cockatiel, Gracie, will fly to my shoulder every time I walk in my room. But, she won't get on my hand. I just don't get it.

What should I do to get her used to my hand?

Hold a piece of millet spray in that hand lol. For a while at least, the only time she gets an opportunity to eat millet spray should be while you're holding it for her. Millet is a great training treat because it's long, and you can adjust the way you're holding it to bring her closer to your fingers when she's ready for it. Eventually you can hold it so that she has to put one or both feet on your hand to reach it.

My Trilly is just like that. She is affectionate, will sit on my shoulder or in my lap, adores Paul and always hovers around him... but when she sees a hand approaching it's the signal for her to take off.
It's weird to see such a domesticated bird being so anti-hands!
The millet training worked with other members of the flock but she refuses.

One of mine doesn't like hands too much...
I over came this by just sticking out my
index finger, with the rest of my hand clinched into a fist shape... he seems to think its the perch... LOL works for me now..

I got her from an abused home, and she came very cheep, a huge cage, her and two other tiels, and lots of toys and food. Want to guess how much? I'll give you a hint.....I'm 14 and I could afford it! (I don't know if UK dollars are the same as american so.....) anyway, she has a very bad past with hands and just doesn't like them. Even though she's tame she will still lunge to bite an unwary hand or finger. Help?

Stay relaxed, be gentle, and go at her speed. And work on the food bribery, it can be a huge help.