Ok, this has bothered me for a long time.

No spoiler warning, because it's been like a decade since this stuff came out.

So Voldemort has this grand strategy, when he's in like high school, that he's going to be "Super Bad Guy Who Punches Death In The Face, Because Bad Childhood I Guess?  Whatever."  He finds out that you can make a horcrux to hide part of your soul, but you have to kill somebody to do it.  "Sure, that's fine, I'm super committed to this plan," Voldemort says, "Hell, why don't I kill like a bunch of people, and make a bunch of them, as backup?"

"Yeah, that's fine, you can do that," says the rules of magic, who probably were just thinking that he maybe got a bit too smiley when killing people was brought up.

Voldemort does this, and puts a bit of his soul into:

• His school diary.
• Like his mom's ring, I think?
• The Slytherin guy's locket.
• The Hufflepuff lady's cup.
• The Ravenclaw lady's diadem.
• His stupid snake.
• Harry Potter (whoopsie).

He then hides these things in:

• Ginny Weasley's shopping cart.
• His family's crappy run-down house.
• That cave place full of poison stuff and zombies that Dumbledore and Harry go to in Harry Potter and the Fucks He Stopped Giving.  This is the only good hiding place.
• The goblin bank?  I didn't pay attention to how they figured this one out, but it's not a terrible idea either.
• The school where everything happens, wow, this is The Best Idea.
• Next to him.  I guess someplace sneaky before he returns to life?
• His actual main enemy.

Here's what I would do, if I suddenly had the chance to become immortal through a series of murders, and wanted to stay immortal, despite the obvious moral questions involved.  My horcruxes would be:

• A brick.  I'd hide this in a building made out of like, a bajillion bricks.
• A big heavy rock.  I'd hide this at the bottom of the damn ocean.
• A really big iron atom.  I'd hide this in "whatever, who's going to find one atom."
• Can I do a second brick?  Seems like the right option.  I'd hide this on the moon.  You can levitate stuff right?  Just be like "fuck off to the moon."
• The Sun.  Your move, The Good Guys.
• Anybody who is not actively my main enemy.  Maybe like a dog?  People like dogs.

Finally, I'd use my standard "I'm immortal" defense against my enemies: Live a long time, quietly, out of the way, until all my enemies are dead, and I'm long forgotten.  Then, you slowly take things over, realizing that there's no need to be flashy and loud about things.