A set of cable covers, or sheathing, is highly recommended. Access to chemicals must be treated with the utmost seriousness. Cleaners and other chemicals should be kept in a closed cupboard. Again, cockatiels love to taste things. Nicotine is deadly to the cockatiel.
Alcohol is also poisonous.
Just think of your cockatiel as a 4-ounce toddler. Curiosity and determination are two dominating traits that cockatiels exhibit in spades. Though you think you've caulked every cracked, sealed every hole and blocked every gap, your bird will find more. Bird-safing is an ongoing process, and one that requires making a few adjustments in daily routine, including opening doors to the outside. You should have a screened porch or some way to keep the bird from escaping to the outdoors.