Information Overload; Some Sort of Plan Should be Involved in Writing a Story

For the first time in my life, I am thinking of doing some planning for one of my stories.
No, I plan to plan everything on this story, because at the moment it is my favourite out of all approx. 30 stories I am simultaneously writing. :3
(There are many dropped ones, hiatus ones, etc, too, though. And most of them are stories that I'll never ever put on the internet as they are only for my entertainment. :3)

Because to me, Four Leaf Clover was a failure. My failure. Rather, the story itself wasn't a failure since I got a good reaction from the FPCom readers, but what I did to it made it a failure.

I never plan out any of my stories.
I usually would just think up of a starting plot or idea, a few characters, then start writin'!

And I now wished a little that I had planned out Four Leaf Clover at least a little. Usually when I write, I would slap new ideas into the story along the way.
Even if my writing works best that way as I usually come up with good ideas as I write, it can bring a bit of a mistake. What I'd added into the story later may not mix well with the start or something that I had said at the start. Four Leaf Clover had this problem.
It has been over a year since I'd started Four Leaf Clover, and I forget what I'd written down before. But then when I re-read back, I realised with some horror that what I said at the start contradicts with what happens recently. I was worried that the readers might notice. New readers who reads the chapters all the way through will probably notice it, old readers who waits for new chapters probably won't. Hopefully.
(And don't ask what the mistake was; I'd already forgotten. I remember worrying about it when I re-read the first few chapters though... O.o)

It was worse since Four Leaf Clover had potential, I just knew. If only I didn't stuff it up, it could've been way way better than it is. I feel that I own something to the readers and the story itself. I've become attached  to the characters already anyway, since I've been with them for over a year already.

And so I do not want to make the same mistake all over again.
At the moment my focus are on 3 different stories, with Four Leaf Clover as one of them. It never leaves my "focus", mind you. There are people waiting for me to update. >.>
2. My World, Your World and The World - an action mecha supernatural story, I guess. Supernatural powers are known to exist in this universe, our earth in 2047 AD. The main character becomes a member of a world-wide organisation sponsored by the UN that researches, controls, investigates, etc, crimes and criminal that are related to the supernatural.
3. The Absurdly Powerful Student Council. Literally. - a school life supernatural comedy story. Set in a country where there is a school that keeps its secret within its huge impenetrable walls; it was also widely known as the most prestigious school in the world and the entrance exam seems to be insanely hard. Kiriha, the main character, suddenly gets a "mandatory" invitation to this school after meeting its Student Council one day. She goes there and was told that this school was created to house kids who have supernatural powers, magical powers, are non-human beings, etc, and that she was also one, without knowing it. The Student Council were made up of only the strongest students, so the title rings truth.

At the moment I'm attempting to plan out My World, Your World and The World, but I seriously do not know where to start. There's so much to write about, which also means that there's so much to plan of!
Seeing that it was set in a different universe (similar to the current world, but still different), I decided to draw out the map of the setting, but that failed... Then I decided to list the characters, but that... sort of failed as well.
And so I went on to creating some cases for the team to solve. I instantaneously came up with three, and am  glad that I am planning them out before writing as it will likely give off the best product. ...probably.
However this sort of story can go on forever; it sounds episodic, and episodic stories seems to last long (not that it will be popular or good long, but that the story itself can be long) as they can really go on as the author gives them some new problem each new episode. But I don't really want this story to be episodic, so I'll need to think up some sort of ending... but I can't really come up with any. Not at the moment anyway.

And I need to start planning for The Absurdly Powerful Student Council. Literally., too...

And I am planning on planning for the future of Four Leaf Clover, and just so you know, it will be a long long road...
I have no intention of ending it any time soon, as there's a lot more that I can still write about... there are quite the amount of characters after all... and I can write four times more than a normal story, because the main character leads 4 lives!!!