Childproofing your iPhone, iPad, or iPod Touch

Kids are awesome and they do love those iOS devices. Here is how to child-proof that iOS device before you hand it over to your kid or nieces and nephews.
A. Device itself.
These are no brainers, usually kids (or even adults) are not as gentle on devices as you would want to be.

1. Screen protector
2. Invest in a case (plus points if it has a hand-strap you can have the kid wear) or is really tough ala otterbox or even better LifeProof
3. Backup your device regularly – you should be doing this even if you don’t lend your device to a child.

B. The OS or operating system

1. Keep passwords secure, may it be the device password, Apple ID password or your restrictions password.
2. Enable Restrictions – This is a powerful feature available on ALL iOS devices that is seldom used by most people. 

Restrictions…
Settings > General

> Restrictions > At first run you will be asked to enter a restrictions password. Choose a password. Make sure you keep this in a safe place away from kids.
There are tons of settings that you can turn on or off before you hand over that iOS device to a kid.
 

Important = DISABLE IN APP PURCHASES (I have personal experience of kids buying stuff on my iPhone because I forgot to turn this on)

C. Screen the apps that you allow the child to use.
D. Limit their time on the device.
E. Turn on Find My iDevice.

To turn it on: Settings > iCloud

This is important especially if the child cannot speak yet. You can lock the device, find the device and make the device chime or make a sound so you can find it easily. - suggested by my friend @JaysonNg