Apple produces good quality devices that can last you for years. But wear-and-tear is still an issue, and eventually, all electronics will see their demise. Still, by taking precautions, you can keep your device alive longer and get the most for the money you spent on it.
Get a screen protector. You may think it is not necessary. Your screen may not get scratched or visibly damaged in any way without one. But the constant tapping and stroking of the device does wear down the innards over time. The screen protector helps absorb up to 50% of this impact. Replace screen protector at least once a year. If you need help installing one, many stores that sell them, such as mobile phone dealers, are willing to do it for you and have tools to make the task easy.
Use only Apple branded or approved chargers. Avoid using knockoffs, such as those purchased for lower prices in non-Apple retailers or online. See warnings for more details.
Use an Apple branded or approved cover. This can better help absorb falls and bumps that are an inevitable part of life. Many other companies make covers, many of that are quite beautiful and often have interesting features. But they lack the same advantages.
Turn off your device when you are not using it. This helps extend the life. For iPhones, turn the device off at night when you are asleep. Keeping it powered down 33% of the time when you don't need it can translate into up to 33% longer life. Additionally, the battery will not drain much while it is powered off. Presumably, an iPad will be used even less than an iPhone. Since it does not receive calls, it does not need to be on all the time. It can be powered down at least 50% of the time, if not much longer.
Do not charge beyond 100%. When charging hits 100%, pull the plug immediately. To be on the safe side, charge to 90-something percent, then pull the plug. There is not a huge difference between 97% and 100% battery. Avoid making overnight the time you charge up your device. Charge some other time of day, such as during the evening before you go to sleep. If you turn off the phone then, you will have a freshly charged battery in the morning.
Close all apps every 2-3 days. Do this by double-clicking the home button, and the open apps will appear. Hold down one of the open apps for a few seconds, and they will all wiggle. Then tap the - symbol on each app you wish to close.