wadaholic

Here are the good ending requirements:
1) At chapter 2 you should find the graveyard (you should pass it when being on the road to the storage room). The radio voice will tell you to not go there if you have found it. Defy the voice and go there. You will meet the invisible ghost down there who will break every object on his way. Don't be scared, you can take him down easily with some bottles or rocks, etc (or a firearm like shotgun if you have found it already). When you have dealt with him, collect everything you see (box loot is optional though) and after that, find a wooden object which seems to block some king of a hole. Break the object and jump into the hole. You will find yourself at weird place. Break your path trough some breakable objects and you should find a note (letter). After dealing with the note, go further and you will find yourself at the storage room. Continue going the story route. If you haven't reached the elevator to the next chapter, you will not hear anything about Leda from the radio voice, he won't say anything though.
2) At the end of chapter 3, as you remember, you should have dealt with the boss. You should NOT kill him. When going through some sort of cafeteria rooms, you can notice locked room. At the other side you can see the hole in the wall. You can easily reach the other side with the main route. When finding that hole, you can notice a switch when watching trough the hole. Throw something in the switch and it will open the door nearby. In the unlocked room you can find police armor and stick of dynamite. Save it for later. When reaching the boss room, you should fine a wall which is shattered a little bit. You should blow it up with stick of dynamite and it will unlock the secret passage to the elevator which will lead you to the next chapter. I repeat, you should NOT kill the boss while doing all this stuff.
3) At chapter 4, you can meet the wall of flesh blocking your way to the exit door to the next chapter. DON'T destroy it. In the room where you can find components of molotov cocktail you can also break some wooden object there: they are blocking your way to the toilets. At the revealed place, you can notice a switch with flower drawn above it. Push the switch, and then you must go back to the hotel, to the second floor where you should have passed the route with the stalkers (monsters, who will stand and don't move while you are watching on them). Pass it again, the ending door which you have probably closed when running away from the stalkers will be opened. Go to the next room, the door with the flower will be opened. There you can find some useful stuff and a ventilation shaft. Go in it. There will be 2 ways which you can pass. 1st is to the right which will lead you back to basement. The 2nd one is longer route. When you pass the 2nd route (which NEEDS to be passed) you will find yourself at the other side of the wall of the flesh (if you haven't burned it yet, though it shouldn't be burned if you are going to achieve the good ending). Go to the exit door.
4) At the chapter 6, when passing the dark labyrinth near the end of the chapter, when you will reach the door which will lead you out of the labyrinth. The radio voice will tell you to use it, but you SHOULDN'T use it. Continue the way: there is one more path which will be near to you. That path is filled with invisible ghosts, they will attack you only if you have taken the wrong direction. If you have passes the route successfully, you will find a room. It is the ordinary room which is not fitting the labyrinth atmosphere anyhow (XD). There will be the table with the note on it. Take the note and open the door which will be near to you. It will bring you back to the exit from the labyrinth. Continue the story route.
5) At chapter 7, when reaching one of the corridors which should lead you to the armory, you will confront some weird zombie-like things. The radio voice will tell you to kill them, but you should just leave them alone and continue the story route.
6) Mostly the same thing at the chapter 8. When reaching the place, where this zombie-like things will be blocking your way, take your view to the right. If you look carefully, you can notice the passable hole in the fence you will be looking at. Go to that way and you will reach the secret room. From there you can go further and you will meet the locked door. Near you there is a prison-like cell. There you can notice a hole and a switch. Throw something into the switch trough the hole in there and the door will open. If you haven't killed the forgotten ones (those zombie-like things) and passed that route (the one which I was talking about in this message section) you can go further to the story line.
If you have done all this requirements correctly, you will reach the good ending.

Thanks ^^ I will surely try!

Well, good luck with that and don't make my mistakes.