tlorber,
When you say misfire, you mean that cylinder isn't firing at all...all the time, it's dead!
The obvious first step would be to replace the plug and look closely at the cap. It might be as simple as sticking a new plug in it.
If things get serious, the next step would be as you alluded to, and that would be a compression check.
It's easy to swap wires and plugs and see if the problem follows either of those items, but the no-brainer first thing to do would be to replace the thing that doesn't' seem to be working, and that's the plug! Keep us posted.
Stuart
