Here is an example of one way to train a parrot that has issues with hands to step up, which I developed through years of presenting parrot-training demonstrations.
I place the hand I want the bird to step onto at the end of a perch; essentially, I line my hand up so it becomes an extension of the perch. I have treats hidden in my other hand.
I teach the parrot to orient her head toward my treat-hand by offering her a few bits to snack on.
Once the bird is aware that my closed fist contains treats, I move my fist a few inches closer to my step-up hand.
If the bird looks, leans or walks over to my fist, I open it up, and offer her a treat.
I then move my closed fist even closer to my step-up hand. Again, if the bird moves toward the fist, she gets a treat.
Eventually, I end up with my fist behind my step-up hand. At this stage, the bird is close enough for her foot to touch my step-up hand.
If she does touch my foot, I reinforce the bird generously. This process can be the most difficult part for a parrot with a fear response toward hands. It may take a few sessions for the bird to fully overcome its fear and master making contact with the hand; however, once it does, it quickly learns to lean over the step-up hand to earn a treat, and to finally place a second foot on the hand.
I continue to hold my step-up hand steady at the end of the perch until the parrot repeatedly, and confidently, side-steps onto my hand. It is at this point that I start to rotate my hand position slightly with each repetition. My goal is to eventually present my hand in front of the bird to cue stepping up.
If the parrot tries to lunge at my step-up hand, I remove my hand as well as the treat hand. This communicates that aggressive behavior causes the bird to lose the opportunity to earn treats.
This only has to last a few seconds, and it will decrease aggressive behavior. I then return my hands to their positions for training the step up and continue to work through the process.