Summarize this article:

Many electricians use electrical tape to make a final wrap or two around each switch to cover the screw terminals prior to installing the switches into their boxes. This is intended to reduce the risk of accidentally shorting things to the terminals. Double-check that all connections are proper before carefully packing the wiring and switches back into each switch box. Screw the switches into their boxes, being careful not to nick or pinch any wires.  Turn the light/device on and off with one switch, then off and on with the next, then off and on with the last. If changing any switch (up or down) does not turn the light/device on or off, regardless of the settings of the others, turn off the breaker and re-check your wiring. There are 8 possible combinations, when using three switches (on and off). They should all function properly.

Summary:
Perform final assembly of the switches and wiring into their boxes. Restore electricity by turning circuit breaker back on. Test all of the switches.