So you're planning to take your broken iPhone/iPad/Macintosh to Apple...
Apple's customer service is excellent and is one of the reasons people are willing to pay a little more for an Apple device. However, there are a number of things to keep in mind if ever you need to make use of Apple's Customer Service to repair or replace your iPhone, iPad or Macintosh:
1. Call in advance
Even if you don't think your device is covered by Apple's warranty, it's always worth calling their customer support number (133 MAC, or 133 622). Just be prepared to be told that "I'm sorry but your device isn't under warranty and I can't help you". Keep in mind that you have free phone support (for all sorts of Apple-related queries) for 90 days after you've purchased an item.
If you take the time to explain your problem clearly and succinctly and are polite the Apple Support tech on the other end might surprise you with how much they will do to solve your problem. But don't fret if they aren't able to help because there is still the Apple Genius Bar
2. MAKE A BOOKING!!!
I can't stress this enough. Not everyone lives just around the corner from an Apple Store so a store visit is usually tacked onto another planned trip. It can be very disheartening to make the trip all the way into the Apple Store to drop off an item for repair and then be told that you have to see an Apple Genius before you drop it off AND then be told you have to make an appointment to see the Apple Genius.
Making an appointment is pretty painless. If you have the Apple Store App on your iPhone or iPad you can just select the store in the App and make a Genius Bar appointment right there. If not, just go to Apple's online reservation page here, select your store and make a reservation at a time that suits you.
3. Back up your device
Ok, so you should be backing-up your device anyway (You are backing-up right? Right?!) but you can make your Genius Bar appointment go more smoothly if you have the right answer when the Genius asks you "Have you got a back-up of this device?" (Hint: The right answer is "Yes").
If it turns out that your iPhone/iPad/Mac needs to be reinstalled or replaced this is a very simple process if they can just erase your device and reinstall or replace it. No one wants to spend the time waiting for a backup and then reinstalling that backup on the new device.
With this in mind, be prepared to walk out with a replacement device. If that's your iPhone that means it won't have any of your information on it. So make sure your contacts, calendars and notes are being sync'd with iCloud so you can just sync them again before you leave the Apple Store. If you've got important text messages remember that you won't get them back until you get back home and restore your iPhone backup using iTunes (Don't rely on restoring your iPhone from an iCloud backup over WiFi in the store. It can be a slow and painful process)
If you follow these steps your Apple Support experience should be a positive one.