One of the challenges of new technology, including iPhones, iPads and iTouch devices, is that inevitably the younger generation are keen to get their hands on them, mostly for games. Whether the games are free or not, you still have to have an Apple ID to be able to "purchase" and download them. That's all very well, but if you have an Apple ID with your credit card attached, you certainly don't want to take the risk that the kids might download loads of stuff without your knowledge, or even by accident, costing you an absolute fortune!
There's a good way to deal with this, but first you need to know one of the tricks of the App Store. When you first receive your iDevice (iPad, iPhone or iPod), you need to create an Apple ID. Many people do this at the prompt during setup of the device. Once you've filled in all your details, you are then asked for payment information. At this point, there is no option to choose None as the payment method. You are forced to enter some credit card information in order to be able to continue. For some people, this is not ideal - maybe they don't have a credit card, or maybe they simply don't want to use it!
The best thing to do is to use a different means to create your Apple ID. Simply skip the Apple ID at the setup stage and go directly to the App Store. Find a free app, any free app, even the iBooks app that you'll automatically be offered. When you choose to download it, select the option to Create An Apple ID. At this point, because you are downloading a free app, you will be given the option to choose None as the payment method. Now we're talking!
Of course, you can easily add payment information afterwards if you wish, but that's not the point. The point is, for example, that you can create an Apple ID for your child with no payment information attached. This means that they can never spend money by mistake. This is most useful when they have their own iDevice and you want them to be able to download free apps.
But what if they then want to pay for some apps? Simple. You buy them a Gift Certificate from the iTunes store using your own Apple ID (which has payment information attached) and then credit it to your child's Apple ID. Now they have a credit balance that they can use to buy apps, but they can never spend more than what you've given them. This gives you excellent control over their spending and also helps them to learn the value of money!
One more thing to remember, and this is a really, really important one - when you download an app from the App Store, or you are asked at any point to enter your Apple ID and password, there is a certain period of time after you have entered the password in which you will not be asked to enter it again. For example, you decide to update all the apps that have updates waiting, you hit the Update All button and you enter your Apple ID and password. Once the apps are all up to date, you give your iPhone to your child to play on. For a certain period of time (maybe as much as 30 minutes), you will not be asked to enter your password again, even if you decide to buy an app. This means there is a period of time where your child could download anything they want, deliberately or otherwise, without needing to enter your password. Be careful, it happens - A LOT. I know people whose kids have spent €300+ in a very short time using in-app purchases, because the password had already been entered and the adult wasn't aware of this problem. So watch out, be careful and - have fun!