for my dwarf jigglypuff, she thought when I picked her up it meant she was going to go somewhere.. she didn't really get that I just wanted to hold her!.. So i began to reward her with a tiny bit of cheese when she would sit in my hand without fussing and/or nipping "hey mom! put me down somewhere already!"
it made her happy to sit in my hand that time, but it does not seem to train them to always sit nice. I duno, dwarves are kinda.. light of brain.