Always turn off the power at the consumer unit first!
Start from one side, put the yellow in common, red in '1 way' and the blue in '2 way', doing the terminal screws up securely as you go.
Then the next set (they are the other way up) put the wires in similarly numbered terminals, then the last set.
Screw the faceplate back to the wall.
Turn the power back on and see if everything works as you want it.
If the switches are the wrong way around, turn off the power and start again.
Adam
April 2010