Traveler wires are interchangeable. In the 1st diagram below a 2 wire nm cable supplies power from the panel to the first switch box.

Adf Home At End Of Run Switch Wiring Diagram Wiring Resources
How to run wire for a three way switch. The two hot wires of three wire cable connect to a pair of. A 3 wire nm connects the traveler terminals of the first and second 3 way switch together. You will see a black screw and two gold screws on the switch. 3 way switch 2 3 way wire which has black white and red coated wires and of course a copper ground wire electrical boxes of appropriate size to hold 3 way switch and wire. End of run lights controlled by two three way switches these end of run lights are controlled by two three way switches with a two wire cable power source coming through the first three way switch. You should have three remaining wires in each box.
The black and red wires between sw1 and sw2 are connected to the traveler terminals. This might seem intimidating but it does not have to be. Take a closer look at a 3 way switch wiring diagram. In this diagram the electrical source is at the first switch and the light is located at the end of the circuit. 3 way switch wire diagram power to light switch. Tipthe white or neutral wire goes completely through the connection system with pigtail connections at both switches and the first light box.
This 3 way switch wiring diagram shows how to wire the switches and the light when the power is coming to the light switch. Wiring diagram 3 way switch with light at the end. Strip all three wires with wire strippers. In this diagram the incoming hot wire attaches to the first switchs common dark colored terminal. 3 way light switch wiring diagram see below. Take your three way switch.
You dont need the other terminal on the three way switch so its fine to cover it over with electrical tape to ensure the terminals dont get mixed up. To use a three way switch as a single pole one connect the hot wires to the common terminal and the traveler on the same side of the switch body. Two black and one red. Remember the black wire that you wrapped around the traveler wires is the common. The black line wire connects to the common terminal of the first 3 way switch. Three wire cable runs between the switches and 2 wire cable runs to the light.
Pick the diagram that is most like the scenario you are in and see if you can wire your switch. A non contact voltage tester. With these diagrams below it will take the guess work out of wiring. First run a 2 wire cable from the wall power to the black screw on 1 of the switches. Wire cutters and strippers. Typical 3 way switch wiring nm cable.
To wire a 3 way light switch youll need 2 3 way light switches 2 2 wire non metallic cables 1 3 wire non metallic cable and 2 6 inch grounding wires.