Now why would you play through with a guide first? 
Messing everything up big time is fun.
My first playthrough, I avoided the spoilers about the murderer and actually got the Bad End.
Not the 'I don't know who the murderer is' Bad End, but the 'your little sister is dead, and the kidnapper is probably going to escape justice if you don't take it into your own hands. What do you do?' bad end.
It was epic and depressing and fitting as hell. I was aware of the New Game + function, so after realizing I had no chance at maxing the social links I ended up focusing on maxing my stats and finishing a few of the social links instead. After ignoring/not having the stats to complete them, I basically raced to finish the Nanako and Dojima arcs as fast as I could, which were definitely some of the most touching and emotional character arcs I've had in some time.
I actually finished both of them the week before the kidnapping, to the point that on one of the last nights I had one of those rare moments in which Nanako and Dojima are both home at the same time. At some point along the way I was head-canoning that Souji was pretty distant and adrift without a sense of his own family, and so after Nanako's arc and the bit about both her and the PC finding a sibling, and Dojima's conclusion about how they're all a 'real' family, it was a heart-touching moment of the family all together. Then there was the school festival and family involvement, and then...
Man, I've never been so emotionally invested in a Bioware game as I was in the climb through Heaven. I nearly bankrupted myself paying the fox to restore my magic rather than rest for the night, and it was an extremely uphill fight to beat the boss. Nanako was rescued, and in the hospital...
The next, last weeks passed in a daze. Every chance I had, I went to the hospital. I powered through the Sayoko social link on the basis of justifying visiting Nanako during the night shift. I found a co-miserator in Yumi, who was also going through the slow motion destruction of her family in the same hospital, and her misery just made the whole thing even more depressing.
And then... then...
It... it can't be true. It can't be. He...
I DIDN'T CARE ABOUT THE METAGAMING. I DIDN'T CARE THAT I HAD 30 MORE LEVELS TO MAX. I DIDN'T CARE THAT THERE WERE ANOTHER THREE MONTHS IN THE GAME. I DIDN'T CARE THAT I KNEW THERE WAS A CHRISTMAS EVENT. I DIDN'T CARE THAT HE CLAIMED TO NOT KNOW. I DIDN'T CARE ABOUT THE DISREPRENCIES. I DIDN'T CARE I DIDN'T CARE I DIDN'T CARE. THERE IS ONLY FOG AND IT WILL BE RED!
HE KILLED NANAKO
HE KILLED NANAKO
he killed nanako
he killed nanako
And so Nanako died. Retribution was metted out. The Truth was lost.
Time flew past, but nothing was remembered. Nothing was worth remembering. Dojima looked like how I felt. Devestated. Defeated. No longer caring what happened to the world. There was nothing worthwhile left in it.
So I got on the train, left miserable backwoods Inaba, and closed my eyes...
[Would you like to play a New Game +? All your experience will be carried over.]
... and woke up once the train to Inaba, where I was to spend the next year. It was surreal, a sense of deja vu you can't shake or avoid. I thought it was a dream, a memory. I was a passenger in my own body, barely able to escape the tracks of fate as history repeated itself. The announcer died. Saki Konishi died. Chie nearly died.
But Nanako wouldn't die. Not this time. This time would be different.
THIS TIME I WILL SAVE NANAKO.
Even if I have to struggle through this mystery a thousand times in a thousand different lives, reliving this same year each time.
This is my New Game +.
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And that, my friends, is how you role play New Game + into a JRPG like Persona 4. I did every possible bad ending before allowing myself to get the True End.
I actually head-canoned a dark fanfic based on the above, in which New Game + was sort of a ground hog's day loop in which Souji is stuck repeating the year until he can win. Except that failure is a lot easier, insanity difficulty hard, and Souji's approaching an event horizon because no matter how many times he's tried and failed, he has yet to save Nanako. So he tries to game the system, and everything starts off great but goes to hell.