This diagram and video demonstrates how to wire you pickups for series/parallel switching in a Les Paul, using push pull tone controls.
Most pickups are wired in series, its what gives it it's full and beefy sound. Putting the pickups in parallel, gives a single coil-ish tone but with a noticeable loss in output, resulting in a very thin sound.
Note - this wiring diagram is colour coded for House of Tone or Seymour Duncan pickups.
Similar Wiring Diagrams
3 Humbucker Les Paul (with push pull pot for middle pickup)
Coil Split Les Paul (modern wiring)
Coil Split Les Paul (50s wiring)
Switchcraft Toggle Switch Wiring (Read our step by step guide on how to wire a Switchcraft toggle switch)
Les Paul/SG Junior (refer to our guide on wiring a Les Paul Junior)