Try this recipe, and be sure to cook up a pile of root vegetables and cabbage to go along with your meat. They're fabulous cooked in the beef stock!
Step 1: Boil meat
If you live in New England then you've probably got a choice between pink and gray pieces; go for the gray one, which hasn't been chemically treated to maintain its color. Those of us in the rest of the country are doing well to get our hands on corned beef at all.
Cut open the package, and dump the meat into your large pot. Fill it with cold water enough to cover the meat, and put the pot on to boil. Your corned beef will either come with a seasoning packet, or the meat will have been packed in loose seasonings; either way, make sure the seasonings make it into the pot as well. Don't was the meat or trim off any fat; it just goes straight in.
Keep the pot at a low boil for a couple of hours, or until you can easily stab through the thickest part of the meat with a paring knife. Add more water to keep the meat covered. The cook time will vary depending on size.
You can use a pressure cooker to speed things along if you're pressed for time. My cookbook recommends cooking a chunk of corned beef for an hour at 15psi, but I found this was much longer than I liked, and I haven't tested and optimized timing for the pressure cooker. If I've got time, I prefer to let the meat simmer on the stove all afternoon. The house smells fantastic, it takes no effort besides an hourly water check, and it's impossible to screw up.
When the meat is done, remove it from the pot to cool. Tongs are great for this. Reserve the liquid in the pot- we'll use it next.