To take screenshots with you Samsung Galaxy Device in the easiest way ever, just do as follows:
1. Open "Setting" App
2. Find "Motion" and make sure it is enabled
3. Tap on "Motion" to see the settings
4. Enable this feature: "Palm to Swipe Capture"
5. Now, Swipe the screen from Right to Left (Or Left to Right) with the side of your hand
6. Your Screenshot is ready :)
*Note that, your Galaxy phone must support the mentioned motion. If Not, see the following tips: