Be prepared for an afternoon-long event. You will
have to remove things to get them out of your way. This may include fuel rails, PCV vacuum tubing, EGR sensors, EGR valves, power steering reservoir mount, and more. Just take your time and mark everything as you go along so you don't forget what goes where. If you do remove fuel rails, remember to spray the O-rings with WD40 or other oil-based lube before reinserting the injectors into the rail or engine.
It's not a difficult job, but it does take a while and access is tight in some areas, especially near the firewall, so swivels and extensions will be important, as tarajerame
said. A proper "spark plug" socket will also help. I second everything the guys before me said, too. Tighten to 28 lb-ft of torque and no anti-sieze. Make sure to get some dielectric grease for the COP boots. In fact, you may want to look on eBay for a full set of COPs for under $100 (try Global Automotive
or Uneek Supply
). Depending on your mileage, weather and driving habits it couldn't hurt.
If you want to upgrade the spark, go all the way with Denso Iridium (IT16) plugs; otherwise get Motorcraft plugs, as code58
And I've heard using fuel line hose to begin threading the new plugs will help prevent cross-threading, though I've never had a problem with this. I just start it with the extension on the spark plug socket, then attach the wrench after it's started. Same effect.
You'll probably find even more tips or a whole thread if you search the forum. Take your time the first time and when you're done you'll be happy you've done it yourself, know it was done right, and saved $300+.