Training a cockatiel (or any bird) takes a great deal of time and patience. You must first gain your pet’s trust, and then you must ensure you never lose it. To accomplish this, you must be careful not to lose your temper with your bird and never hit her. Birds are very sensitive, intelligent creatures who do not deserve to be hit, no matter how you may feel in a moment of anger.
Although parrots are clever creatures, they are not linear “cause and effect” thinkers. If a parrot commits action A (chewing on some molding under your kitchen cabinets, for example), she won’t associate reaction B (you yelling at her, locking her in her cage, or otherwise punishing her) with the misbehavior. As a result, most traditional forms of discipline are ineffective with parrots.
So what do you do when your cockatiel misbehaves? Try to catch her in the act. Look at your bird sternly and tell her “no” in a firm voice. If the bird is climbing or chewing on something she shouldn’t, remove her from the source of danger and temptation as you tell her “no.” If your bird has wound herself up into a screaming banshee, sometimes a short time-out in her cage with the cover on (between five and ten minutes will do in most cases) will do wonders to calm her down. Once the screaming stops and the bird has calmed down enough to play quietly, eat, or simply move around her cage, take the cover off to reveal a well-behaved, calm pet.