There are 4 different difficulties in DX:MD. I personally used to play on the easiest difficulty, but that isn't the right way to play the game. Just think for a second: what do you like in video games? If you're a real gaming champion athlete you'd most likely say: Overcoming a big challenge. DOOM (2016) first bossfight was a real challenge in any difficulty, but once you killed the boss you felt powerful. Now on the easiest DX:MD difficulty you won't be overcoming any difficult challenges, but that's what you don't want right? You want a little challenge sometimes. So if you're not that good at games then pick the 2nd difficulty. If you're a real gaming athlete veteran champion, then pick 3rd or 4th difficulty.

So you can always go back. Redo the dialogues. Replay some encounters. Try something else. For example the game gives you an option to choose from 2 different missions. Don't worry, play both. That way you can get the full experience.

You can play both ways, but the game really favors the stealthy approach.
YOU HAVE TO EXPERIMENT! SAVE THE GAME A LOT!
In the higher difficulties you can be killed pretty easily, so you should experiment. If something goes wrong you can always try doing something different. Try different passage ways. Crawl the vents. Do stealthy take downs. Or just go and ♥♥♥♥♥♥♥ kill everyone with your Typhoon augmentation.

The hub world is very detailed. So try to go everywhere. Find everything. The world is full of so many different little details. Go find them. Did you know that Jim Miller is gay? Well, if you're playing the right way (exploring and also taking your time to have a look around) you should spot that little detail in his apartment.

There are so many different ways to play the final mission. Play it many times and try to play differently every time that way you can see all the endings. For example on my first playthrough I got the best ending (I didn't know about the different endings). On my second playthrough I got probably the worst ending. Now that's what makes this game so great. How do you want to kill the final boss? There are so many different ways. Again, experiment and explore. Maybe you can even avoid fighting overall? Go and see. https://www.youtube.com/watch?v=ba1fRXmcric

Do all the side quests if you're a real
gaming-athlete-champion-godmode-super-ultra-mega-gamer-dude

Images used:
Jensen VS Marchenko[wall.alphacoders.com]
Funny Adam Jensen[www.deviantart.com]
Jensen with a cigarette[www.artstation.com]

Hope you enjoyed the guide!