If you do get caught, don’t give up — just take cover!
If you’re crazy, like I am, you can just suicide every time you get spotted by enemy soldiers because you want to go for perfect stealth. But the game isn’t really meant to be played that way—every mission is full of dumpsters to hide in, grass to crawl around, and all sorts of secret passages that’ll let you dodge the heat for a while. If there are baddies firing at you from all corners of the map, do yourself a favor and run for safety rather than just killing yourself. Hide out for a while and they’ll lose track of you.
Be aware of checkpoints.
There are no manual saves in MGSV—you’ll have to rely on the auto-save system, which can be a little fickle. Keep an eye out for when the yellow “saving” marker appears on the top right. If you notice that you haven’t reached a checkpoint in a while, you may want to play more conservatively. Some bases can be pretty complicated and there are few things worse than having to repeat 15 or 20 minutes of pinpoint stealth because you just got blasted by an enemy gunship.