Well the main thing you need to know about cartilage piercing is that it hurts! Painful and I believe it can be more prone to infection. Be prepared before you go in to have it done!
It takes a few months until it heals completely, few months in which you should not take the piercing off or else the piercing will disappear. It will hurt for a few days when you touch it and also you will not be able to sleep on the side you made the piercing because it will hurt you.
Cartilage piercing (nose and top of the ear) takes longer to heal and is more prone to complications. Your piercer should give you aftercare instructions specialized for your cartilage piercing.
You want to make sure that the piercing place you go to will use a sterlized/packaged needle. If the cartilage is pierced with a gun, the cartilage with shatter and there will be a bump on the back. After you get it pierced, make sure to clean it everyday.
Before a pircing goes through cartilage, it has to penetrate skin. This will hurt unless you are under some sort of local anesthetic, or have had a couple drinks. The great thing about piercing cartilage is that if you change your mind it will heal up.