They have the similar rules as a bird. Bring your hand to them slowly, in front of them, and under their feet. Then move your hand up to just above what they are standing on. If they are ready, thier natural instinct to step up kicks in just like a bird. At first they will step half way onto your hand leaving their rear legs and tail tightly around a branch.
With my free hand I’ll gently rub their feet to get them to release. The same works for their tail. I gently rub it until they release. As soon as they are on you, make sure thier tail wraps around your finger, wrist, or hand. I do not walk with them until they have their tail in position.
Also Just like a bird, never grab them from their top back or force their feet off of a branch. Let them step on you when they are ready. Give it time and never force them and they will reward you when they are ready. I've found that my males get bored with their cage and want to come out around 9 months. I guess they want to look for chicks?
This is by no means fact, just my experience.