Accessing and Quitting Open Apps
When you finish with an app and push the home button on the iPad, you aren't really quitting the app. Instead, you are mearly just closing the app from view, much like closing a window on your computer. This may not seem like a very important fact to most, when in reality, it could save you time and battery by following these steps.
If you have a number of apps installed on your iPad and it takes a bit of time to scroll through your different pages to find an app you use frequently, you may want to consider pushing the home button twice to access the apps you have open. By pushing the home button twice you will see all the apps you have open. Here is a view of some of the apps I currently have open on my iPad.
If I want to switch to a different app, I just touch it from the list. If more than seven apps are open, more will be available if you scroll your list at the bottom to the right (touch on the right and move finger to the left). So if I'm unsure where an app I opened earlier in the day is installed, I can press the home button twice and search for it in the list, thus saving some time. This trick can also be used from within an app as well.
Saving Battery Power
While it is convenient to have multiple apps open at one time, having too many open can quickly drain the battery. To save on battery power quit, not close, an app by puching the home button twice and then touching and holding on an app in the list for a few seconds. Once you do that, you will notice the apps begin to shake and a small red minus sign appears in the top left. Here is an example of what you should see.
To quit an open app, touch the small red minus sign in the upper left. You can still scroll to the right to see all your open apps, closing the apps you wish. When finished, simply push the home button once to make the minus signs disappear.
Just remember, if you want to be slightly more productive with your time, save some by pushing the home button twice to navigate between apps. If you want to save battery, push the home button twice and then press and hold an app for a few seconds. They you can close as many apps as you wish.