Help: Spark Plugs

[kklann]

I want to change spark plugs by myself, but somebody says I have to pay close attention to two thing:

1. Clean the outside of the old spark plugs before remove them.

2. The torque must be precisely as stated.

My questions:

1. How to clean the outside? Need special tools or material?

2. How to measure the torque? Or it is not that important?


Or, any other things to know?


Thanks a lot.