I am not a great cook by any means, but one thing I do exceptionally well is roast a turkey -- never dry, never tough, never bland. A few tips.
(1) Don't skimp on the oils. I've seen recipes where the instruction for oiling the turkey is 'rub an empty butter wrapper on the outside' or 'drizzle lightly with oil'. Unless you literally have a medical issue requiring you to sabotage your turkey, be more generous rather than less with oils -- whether you use butter, or olive oil, or anything else. (I use butter on the inside and olive oil on the outside.) Unless you eat turkey skin rather than meat, most of that oil is not going to make it to your plate. The entire outside of the turkey, or at least the entire top, should be coated -- it doesn't have to be a thick coat, but it should be as global as you can get it. This (1) gives an extra source of moisture to the whole that won't harm the taste of the turkey; and (2) helps to seal in juices.
(2) Apples and onions make the best stuffing. For stuffing, take enough apple and onion to stuff the whole turkey (you generally want more apple than onion, and the apple should be as tart as you can get) and a half stick of unsalted butter. Use about a quarter of that half-stick to coat the inside of the turkey, and chop the rest into big dabs. Cut the apple and the onion into chunks, removing the less tasty bits; I've found that eighths work very well. Mix up apple, onion, and butter, and stuff it in the turkey. Nothing more is really required, although you can add chopped bacon and (lightly) your favorite turkey spices. It's extremely easy, and it keeps your turkey from drying out. People always go for the breaded stuffings, but I find that breaded stuffings often are culprits in bad turkey -- people are using their turkeys as stuffing ovens and not using the stuffings to enhance the turkey. Any kind of stuffing will help keep moisture in your turkey, but breaded stuffings also tend to absorb a lot moisture.
Apples and onions with butter also give you a richer gravy. If you are cooking your turkey right, you don't need gravy. You should never rely on gravy to make your turkey palatable. Gravy is there for three things: to do something with odd bits, to enhance flavor, and to cover mistakes (like overly dry turkey). You shouldn't be relying on it to make your turkey edible. But the gravy you get with apples and onions and butter as your stuffing is very flavorful.
(3) Basting should be done carefully and with discernment. Basting properly helps keep a turkey from drying out, but most people, I think, don't do it right. You should certainly not be basting more than twice the entire time, and when you do, you should baste well -- don't just use the juices in the pan, which are probably not enough; also use some of the giblet broth that you are using for gravy. Your oven is a humid box. When you open the door, you let the moisture out, thus increasing the amount of liquid that evaporates from your turkey. Most people (1) open the door too often or (2) when they do, don't add enough liquid to make up for it.
(4) Don't overcook. This one is obvious, but something worth noted is that all three of the above points give you more wiggle room than you would otherwise have -- if you do accidentally overcook, it does less harm to your turkey. I overcooked my turkey a bit this year, and it was still juicier than most people have in their best years.
