How to not stumble upon a bad end and see all of the Golden-exclusive content.
Useful Tips (Early Game)
I decided to make this short guide since P4G is notorious for not giving new players enough info to figure out how to get to the Golden Ending and see every Golden-exclusive piece of content by yourself. If you follow it you will get the most out of your first playthrough without reading walls of text or following a walkthrough religiously.
Try to Get Marie to Rank 10 and Adachi to Rank 6 Before 12/24
Prioritise those S. Links. Marie unlocks a new dungeon and the Golden Ending and Adachi adds a lot of new scenes later on in the story. His S. Link progresses automatically after you get it to Rank 6 so don't worry about it.
If you really don't like Marie then you can ignore her completely and still get the original PS2 True Ending of the game. The extra dungeon and the winter segment will be skipped completely this way. This is not recommended since this content is pretty enjoyable (and is considered canon judging by the spin-offs). You will still see all of the Adachi scenes this way.
Get the True/Golden End Requirements
Don't read this until you clear the Heaven dungeon (this is pretty late in the game). I'll try to make it as spoiler-free as possible:
On 12/03 choose the following responces when prompted by Yosuke:
- Wait a second here...
- We're missing something.
- Namatame's true feelings.
- Something's been bothering me.
- We're missing something...
- Calm the hell down!
On 12/05 choose the correct person.
If you decide to protect this person if asked, you will instead get another Golden-exclusive Accomplice Ending. This is on of the "bad" ends, so if you decide to go for it make sure to keep a save before this point so you can continue on later.
On 03/20 talk to all of your maxed S. Links. After the game asks you if you want to go home, select "No" and go to the Junes Food Court instead.
Whether you get Golden or True ending is decided by if you have maxed Marie's S. Link or not.