Push notifications can shorten battery life, particularly those pesky instant messaging and social media apps that alert you throughout the day. Unfortunately, some app developers abuse the notifications system with promotional messages and other spam too. Enough already! To save power on an iPad, go to Settings > Notifications and turn off notifications on an app-by-app basis. This process can be tedious if you have a lot of apps. Alternatively, turn off Notifications Center entirely if you don't want any messages at all.
On tablets running Android 4.1 or later, it's pretty easy to zap notification spam. When an unwanted message appears, long-press it to launch the App Info screen, where you can turn off the app's notifications. Alternatively, go to Settings > Apps, choose the offending app, and neuter its notifications there. If you're running Android 4.0 or earlier, well, the situation isn't pretty. Each app might or might not have an option to turn off notifications. Your best bet: Launch the app, tap the Menu button, go to the app's settings and look for a notifications option.