First rule of thumb when changing spark plugs is to do it when the engine is cold. If you don't have a torque wrench it's ok, you can still tighten them properly. Easiest thing to do is put the new plug in the spark plug socket, attach the extension (8 or 10 in. is perfect) but not the ratchet. Thread the plug in until it is snug, then attach the ratchet to tighten. Most spark plug manufacturers put on the box (especially NGK) how much to tighten. Usually if the plug has no gasket, tighten 1/16 to 1/8 of a turn. If it has a gasket, tighten 1/2 to 2/3 of a turn. For an '05 Accord 4 cyl. they have a gasket.