A drop through wire cage is the best. Make sure the food and water are changed daily. Dietary Requirements Cockatiels need calcium. At one time it was thought that just seed was good enough for birds. This is not true at all.
Protein is important.
Please remember to follow the instructions. More is not better. Some pet manufacturers have formulated well-balanced pellets. Many manufactures have begun offering fortified seed mixes that include the other foods that they need, such as dried fruits, vegetables, vitamins and concentrated food supplements. You should supplement other foods for nutrition and variety, after all the same old diet everyday is boring for birds, too.