Do expect your bill to be larger than what you expected. It simply will be. Do be selective about who gets the number. Each time it rings, think dollar signs with wings. Do be aware of the cultural environment before pulling out the phone to make a call in a public place.
Some people consider it rude or pretentious.
Women will probably find it wise to purchase a cell phone with a fold-up mouthpiece to cover the keys if they carry it in their purse. Use a little household cleaner like 409 on a cotton swab to clean the keys and the ear piece regularly, especially if you loan your phone to others. Don't drive and talk . If a call is urgent, pull over to the side in a safe place and give it your full attention. It may save a life.