There's good advice here. To this I will add that you should be very careful pulling the plug wires off the plugs. There's a right way and a wrong way. The absolute wrong way is to grab the wire itself and give it a hard tug. This is a sure-fire way to separate the wire from the attachment at the plug. Bad, bad, bad. You can't put it back and have the car run.
The proper way to remove the plug wire is to grip it wire at the boot portion which fits over the plug. Be gentle, but firm and the wire will come off in one piece. What you are doing is putting pressure at the actual connection of the plug wire to the plug itself. Do one plug change at a time and you'll be good to go in no time.
