Cockatiels like other parrots have very complex behaviours and social structures. I will try to lay out their behaviors to make as much sense as possible.
Heart Wings: “Heart Wings” are where males make their wings look hearts by pinning the tips of their wings by their side. This is a sign of dominance or that the bird is trying to be macho to attract a female.
Wagging their tail: Some parrots wag their tails just like dogs! It is a gesture of happiness or when the parrot is exited.
Pinning their pupils: Pinning means to make their pupils smaller and is a sign of aggression or agitation.
Raising one foot: If you are not training your bird to do a handshake then it means its giving you the okay to perch on your arm.
Beak Chattering: This is a gesture of happiness, It means “Keep on petting me here!”.
Fluffing up: This is where the bird ruffles its feather to make it look bigger. This means it feels cozy around you and they do this when they preen.
Puffing up: Usually confused with fluffing up this is a gesture of fright or aggressiveness. The difference is that they pin their eyes when they puff up.
Raising their crest: The crest is the long feather atop their heads. When it is raised they are scared or fearful. Try to remove anything in the room that will scare it.
Thank you for reading my article on cockatiel behaviour.
Pet bird behaviours and what they mean. AnnieKKay74 on youtube
10 Secrets to reading body language of birds! ParrotWhisperer on youtube
Reading body language of pet birds by geobeats on youtube