OK so you just purchased your new cockatiel from the pet store and you haven't even given him a name yet. What's the best way to get your cockatiel into it's new home? Normally at the pet store you will be given a small box with air holes in to carry the cockatiel home in.
If there are no other birds in the cage or aviary you are putting the new bird into, then you should place the box on the bottom of the cage and open the flaps. Let the cockatiel come out in it's own time, they will do when ready. Although, if it has been considerably long time and they still do not emerge from the box to get water, then you should tip the box gently ensuring not to harm the bird.
If you are bring the bird into an aviary or cage that already has birds in, it is a good idea to keep them separate by putting the new comer in it's own small cage. This way you can keep your eye on the bird in case it is carrying any diseases that could be passed over to the other birds. One thing to look for is how the other birds react, do they bully the new bird, or does the new bird look like bullies themselves?