How well your rook piercings will go can depend on the anatomy of your ear. Some people have a very pronounced ridge of cartilage, which is easier to pierce but requires slicing through a larger amount of flesh. Smaller ridges don't have as much cartilage to pierce through, but can be more difficult for the piercer to get at. Either way, it's still a relatively simple procedure to an experienced, professional piercer.
All cartilage piercings share the same basic risks and aftercare mishaps. It's important that you follow your aftercare instructions carefully, and act quickly if you start developing any signs of infection. Avoid contact with makeup, perfume, hairspray and other irritants; change your pillowcase daily and cleanse your ear after using the telephone, earphones, earmuffs, etc.
Your piercer will need to determine what gauge is best depending on the prominence of your cartilage ridge. Proper sizing is very important for successful healing. As far as jewelry styles go, your choices are a CBR, mini curved barbell, or circular barbell.
If everything goes right, your cartilage should heal up in 4-6 weeks, but most people experience at least a couple hiccups along the way, which slows things down. Cartilage piercings are tricky, so they usually take 3-6 months to finally get a handle on.