Spraying graphite is really easy. Buy some graphite at the local hardware store (no need to trek to an auto parts store). They come in little metal cans with a pointy tip and the can indicates they're for lubricating auto locks, or locks in general.
Simply take the cover off the tip and place the tip in the lock where you put your key in. Squeeze the can once and the graphite (which is a gray/black powder) shoots into the lock cylender and lubricates all the parts.
Put your key in the lock and turn it back and forth a couple of times which will make sure that the graphite is covering all the parts inside.
You'll probably need to clean your key off for the first few times you use in the the lock as some graphite will come out on the key.
That's it...really simple.
<span style='color:green'>1994 325i </span>- - - 75,000 mi.
No mods - - - very happy as is!
<span style='color:green'>1995 525i </span>- - - 154,000 mi.
No squeaks or rattles... unreal!