You walk with the left stick, you look around with the right, line up your shots with the second left trigger, fire your gun with the second right trigger. (gamesradar.com)
Start off slow using the aim assist lines, but once you get the hang of it, the real challenge comes from lining up those shots on your own. (playstationlifestyle.net)
If he improves there well then lining up shots will become much easier for him. (justarsenal.com)