Use the binoculars
In Metal Gear Solid V: The Phantom Pain, your binoculars are invaluable. Before you begin each mission, it should practically be a given that you look for a good vantage point and scout out the enemy outposts before infiltrating. With your binoculars, you’ll be able to mark your enemy sentries and heavy weapons. It’s a really useful tool for keeping track of where the soldiers are, and also identifying your targets.
When your R&D team levels up enough, be sure to upgrade the binoculars to give it a scope that allows you to assess an enemy soldier’s stats. This will let you know in which areas he’s most skilled, and you’ll at least have some idea of what this guy can contribute to Mother Base when you extract him from the field.