Bearded dragons have a number of body postures. "Arm waving" is usually a sign of submission. Both male and female dragons will puff up their "beards" to appear more frightening and males will exhibit this behavior to impress the females during mating season.
"Head bobbing" is a way for male dragons to show dominance.
Both sexes may "hiss" if startled.
Beardies are usually docile and like to be handled. Dragons should be scooped gently by placing a hand under their belly.