How did they know where to find the next Horcrux?

Question

When anyone destroyed a Horcrux in the Harry Potter movies, how did they know where the next Horcrux is?

Was there a map or something?

Answer 1

• The Diary

  They didn't search for it. Harry found it and destroyed before even knowing Horcruxes existed.

• The Ring

  Dumbledore investigated Riddle's life and important places in order to find it.

• The Locket

  Dumbledore investigated Riddle's life and important places in order to find it. He found it's hiding location but it had already been replaced with a copy. The trio found the locket in Grimmauld Place previously without knowing what it was. They investigate from there to find it's current location.

• The Cup

  Dumbledore theorized that this object was a horcrux. They find it because the Lestranges panicked when they saw the sword that was supposed to be in Gringots. This gives away the horcrux location.

• The Tiara

  Dumbledore theorized that this object was an horcrux. They find it by interrogating the ghost.

• The Snake

  Dumbledore implies that the snake is important in a discussion with Snape. He didn't tell Snape that the snake was an horcrux (or what an horcrux was), but states it in a way that Harry would understand. I don't remember how Dumbledore found or (more probably) guessed this.

• The last one

  Dumbledore guessed that Harry was an unwanted Horcrux. He told Snape who then 'told' Harry.

In summary: Dumbledore did all the heavy work. Harry and friends were mostly lucky.