1. Put the headphones on, without it you can't beat FNAF 4.
2. Turn volume up, I know it sounds terrifying because of loud jumpscares, but it's important to hear all the sounds in the game.
3. Focus.

So basically the first thing you will hear are the running sounds - it's Foxy. He is moving from the left to the right as you hear. It means that if he runs toward the right side, you shouldn't go to the left doors, otherwise he will get in to the closet (the game become a little bit harder now, because you need to check the closet frequently, but don't worry you can still continue).
You have to check the doors from time to time, the higher number of night the more frequently you should do this. When you run towards the door you have to decide, close it or use flashlight. Well, it depends on what do you hear. If you hear the breathing - close it, if not - turn on the light, but before you decide which one action should you choose wait for about 3 seconds at the door. If you play alone in silence you can even hear quiet footsteps of Bonnie and Chica which are really helpful later in game, so you can determine if they are standing next to door or walking away. Sometimes you can hear sounds from the kitchen that means that Chica is there and you can feel a little bit safer for a while, because you don't need to check the right side.
The next thing is the bed - you need to check it from time to time, it's like a time bomb. More precisely it works just like a marionette box from fnaf 2. You have to use flashlight to scare away nightmare teddies or they will summon freddy and they are appearing over and over after a certain amount of time.

This night is a little bit different than the other nights. There is only one animatronic, but it's smarter, quicker and more deadly. There is a way to trick him. As you can hear he is running from the left to the right. You don't need to run like a crazy and pursuit him, just wait until he calms down. After hearing footsteps count to 5 and then go to the doors, that way you are sure he is not moving. Don't wait longer or he may jumpscare you. So basically if he moves wait 5 seconds then move, if he moves again and you counted to 4, count again and then run towards the door.
When you are at the door, flash your light shortly. If he is there close the door and wait until he run away. Of course you don't need to use flashlight, if you are sure he is there - close the door.
It sounds easy, but there is one tricky moment. It's the part when you hear laugh. If you hear footsteps and laugh just act normal. If you hear ONLY laugh, then it's the worst part. He may be everywhere, but first place you should check is bed and the closet, most of time he is in some of this places, if not just keep checking the doors, there is a chance that you will not find him and he will get you.

This part is combination of night 1-4 mechanics and night 5.
Up to 4 am use night 1-4 technique, after 4 am use night 5 technique.

(Feel free to ask questions and I will try to answer them)