Clearing the Cache

If you go into settings > application manager, you can select an app and clear it's cache. Now if you're talking about clearing up the phones RAM there's a built in task manager, depending on the phone manufacturer, that you can use to do this (clear the RAM that is).
 
I use all in one toolbox, simply because I dont want to do it one by one and my maxx doesnt have the task killer by holding the home button.