Turkey is one of the easiest things to fix, but so many have never done it and are a bit overwhelmed.
First off, you want to allow roughly 2 pounds per person so if you have 10 adults, you need at least a 20 pound bird...I would allow 1 pound per child. This will feed everyone well and allow leftovers which are a MUST! Keep in mind that when you look at the tag with the weight, they are including bones...you are not getting 20 pounds of meat and an adult isn't going to eat 2 pounds of it.
When you buy your turkey, it needs to be bought with enough time to thaw or defrost. (I have a former friend who would say "dethaw." Huh?)
To thaw in the fridge you need to allow 1 day per 4 pounds. So, a 20 pound turkey will need 5 days....Thanksgiving is on Thursday. Your 20 pound bird should be bought and in the fridge by Saturday! There is another way to thaw...using a cold water bath, but this is a pain in the tush. You have to change out the water every 30 minutes. It's messy and you have a mushy, gross mess if there happens to be a hole in the wrap. Also, if the bird gets TOO warm, you do run the risk of bacteria in the meat. Just buy it a week early and keep it in the fridge.
Thursday morning you need to get up EARLY (if you want your feast at lunch) and work on prepping "Tom." If you buy that 20 pound turkey, you will need to bake it 3 1/2 to 4 hours. (Until a meat thermometer, stuck in the inner thigh (don't touch the bone) reads 180.) You really don't want a "self-basting" turkey, as that tends to mask the flavor of the turkey (IMHO). At the same time, if you buy a frozen bird, it doesn't get much better than Butterball....again, IMHO.
So, unwrap your turkey, rinse inside and out.
****VERY IMPORTANT**** Remove the bag with the giblets and neck.
Pat turkey dry with paper towels. Oil the skin. (here is where opinion comes into play) You can brush with vegetable oil, spray with cooking spray or rub with butter.
Personally, I like to take a handful of softened butter (quite literally) and rub it over the breast UNDER the skin AND on top of the skin. This will keep the bird moist and will brown the skin nicely.
Sprinkle both outside AND cavity with salt and pepper. Then fill the cavity with aromatics. (I personally don't do stuffing. The thought grosses me out (it also adds baking time) I do a pan of dressing.) I fill cavity with onion, celery, thyme, garlic, maybe lemon slices. You won't eat this, but it flavors the meat mildly.
Tuck the wings under the body to prevent them from browning too much. Tie the legs together. (You want to do this as the legs loosen from the body and the skin will break. You will end up with leg bones and meat just hanging off the body....broken skin and a lot of moisture lost) Some folks say to skewer the opening...I don't because I don't stuff with a side dish.
Put turkey, breast side up, (flat portion down), in a roasting pan. You NEED something heavy-duty. If you do buy a disposable roasting pan, it will need to be put on a cookie sheet or other heavy-duty baking pan. I have placed it flat on the pan, roasted it in a bag (in the pan) and put the turkey on a rack.) I have had success with all 3, so don't freak if you don't have a turkey-bag. I will say this, a bag helps with clean-up as the juices can really stick to the pan. Just be sure to cut a vent in the bag and allow enough room for the steam to "puff up" the bag. You don't want it to touch the top of the oven. My preference is to place it on a rack.
Put the turkey into a 325 degree oven and bake for at least 3 1/2 hours (for a 20 pound turkey). The last 30 minutes to an hour, you might need to tent some foil over the breast to keep it from getting too brown and too dry. You won't do this if you use a bag.
Before taking it out, check for doneness. One easy way is to grab a leg-bone and move it back and forth. If it moves easily, it should be done...or really close to being done. I like to check the temp. I stick a meat thermometer into the inner thigh (where it is thickest...NOT touching the bone) to see if it reads "180." If yes, I remove from oven.
Final step before carving....LET THE MEAT REST FOR AT LEAST 30 MINUTES. Keep it covered with foil to retain heat. Really, this step is very necessary. ANY meat that you roast should sit out for a bit. As the meat is roasting, the juice tends to head to the surface and evaporate. While the meat is resting, the juices redistribute leading to a moist meat. If you carve too soon, a lot of the juice will run out at the first cut.
Carve, either at the table or in the kitchen. (This is what I prefer. I carve it and arrange on a platter to put in the center of the table.)
Well, there you go. I hope this was helpful. Another great help is Butterball...the company. You can go to butterball.com and they can give you MANY turkey tips. They even have a hot line that you can call on Thanksgiving Day to help will any "uh-ohs" or other concerns you may have.
HAPPY TURKEY DAY!