I had a similar problem with my adult male leo. I bought him as an adult as well, and he was really skittish when I first got him. I started by putting my hand in his enclosure for about 5 minutes at a time, to let him get used to the scent/over all presence of something so much bigger than him. Then I built up to gently stroking his back, to hand feeding him mealworms, then short, 1 minute handling sessions, then progressively made the handling periods last longer and longer.