Here are some useful tips and tricks that you can use to make your adventure a little bit easier:

• Play the game how you want to play it. While stealth is one of the biggest draws of Metal Gear Solid titles, you don’t have to use it non-stop. Also, if you feel like killing people, go ahead and do that.
• Crawling is the best way to sneak around, but this doesn’t mean that enemies won’t be able to see you. Avoid lights, even while crawling, as well as not getting too close if you are in their line of sight.
• Try not to go for an S Rank on your first playthrough of a mission. Don’t forget that you can always replay missions by accessing your iDroid, so sit back and take your time when you’re first doing a mission.
• At the beginning of the game, use your Fulton Device on pretty much everyone to build up your Mother Base. Once you start getting into the middle and late game is when you can start being picky with your recruiting options.
• Adapt to your enemies while they adapt to your playstyle. If you notice that enemies are starting to wear helmets, then start shooting them elsewhere instead. Two tranquilizer darts to the legs will knock out enemies fairly quick.
• Don’t forget to use a Buddy that’s perfect for the situation at hand. If you are going to be running long distances, it might be a better idea to bring in D-Horse for that portion, then have another Buddy be dropped in whenever you get to your destination.
• Don’t neglect the Side Ops, as they will begin piling up and important ones might not unlock when they should be available. Not only are Side Ops a great source of income (GMP), you might also be finding great recruits for Mother Base.
• When going for S Ranks on missions, speed is one of the most important factors, and will usually negate the need for careful and stealthy gameplay. As long as you finish quickly and relatively clean, you will get the S Rank.