You can tighten them up by hand by using a long extension onto the plug socket. This is important as you CAN FEEL the thread biting so much less chance of crossthreading than if you just tried to tighten with a ratchet.
Anti-sieze is applied from the factory on 99% of new spark plugs, anyhow most cylinder heads are an alloy and the threaded section of plugs are usually stainless so the two wont really sieze like they used to on older engines.
Copper slip is a no-no as its a conductive grease and can affect the spark deliver if it gets onto the electrode. Molybendum diasulphate based grease is the type to use if you must.
The initial tightening is to crush the compression washer, then re-torque to the correct amount using a torque wrench to create a good tight seal. If you only tighten once than the compression washer may not be fully pressed flat and when the engine warms up you will often find the spark plug is less tight than the desired amount.
