1995 Toyota Corolla Oil Leak

I have an oil leak in an unusual place. My engine started shaking violently at low RPMs. I checked my plugs (thinking one had maybe fouled). I found a significant amount of oil in the sparkplug tube second from the right and a trace amount in the far right tube. I'm assuming this is a head gasket leak but want to make sure before I start buying anything. I'm also wondering if there's anything specific or critically important before I remove the engine head myself and replace the gasket. I don't have the money to take it anywhere and I'm fairly confident in my abilities with a wrench. However, I just want to make sure I'm not biting off more than I can chew.