I think there are two keys to a great turkey.
Brine it overnight in a salt/sugar/ice water combo. Heat up the salt/sugar in a pot of water to get it to dissolve, stir, stir and then let it cool.
Take everything out of the turkey cavity and put it in a bucket or cooler. I use a cooler so it stays colder. Add ice water and the pot of salt/sugar. The turkey will gradually pull the salt in and pick up a ton of moisture.
2nd thing is putting a compound butter under the skin. I use Thyme, Sage and Rosemary. Chop up fresh herbs and add them to room temp. butter. Then I pull the skin up carefully so I don't tear it until I have separated it from the meat. Gotta use your hands for the next part, too. Grab a glop of compound butter and shove it under. Massage it to cover the breast. Once you have the inside the skin area covered, use the rest on the outside of the skin. Drizzle it with oil to protect the butter from burning.
This method adds tons of flavor to the meat. Much better than seasoning the outside. I'm going to do one turkey in the oven and one on the grill.
I'm filling the cavities with onions, lemon, salt & pepper maybe a couple of bay leaves. When I pull this stuff out, I'll put it in the gravy pan along with drippings, flour and simmer until it's ready. Taste at the end and adjust with butter/salt/pepper if necessary. I smash the gravy down to extract the flavor from the onions/lemon and then put it through a strainer for the finished product.