Most Samsung devices will allow you to capture a screenshot by moving your hand from right to left across the screen. It's called Palm Motion or Palm Swipe to Capture on newer devices.

Hold the device in your left hand, and use the edge of your right hand to swipe across the screen. While Palm Swipe to Capture is usually turned on by default, you can check whether the gesture is enabled on your device in the Settings app:

Scroll Capture allows you to take longer screenshots than usual, perfect for when you're trying to take screenshots from a website. In order to use Scroll capture, you will first need to enable Smart Capture/ Screenshot toolbar.