On many Android phones with on-screen keys, getting to Google Now -- the excellent predictive/voice-controlled search app in Android 4.1 and above -- is simply a matter of swiping up from the bottom of the screen. It's not quite as simple as that on the new Samsung Galaxy S4, but fear not, there are still a few quick and easy ways to get to the new Google Search app.
1. At any time, long-press the home key to bring up the task switcher. Then press the "G" icon at the bottom of the screen, in the middle.
2. Put an app shortcut or widget on your home screen. If you're using Google Now a lot, this lets you open it with a single tap. Using a Google Now widget also lets you see cards without opening up the app.
3. From the home screen, long-press the menu key. This will launch you straight into the Google Search bar, and you'll see your Google Now cards below recent search results.
Neither of these area quite as quick as a swipe-up gesture, but if you get used to how Google Now works on the Galaxy S4, it's still easy enough to take full advantage of it.