I take any excess fat within the body cavity that can be easily pulled out and put in a small oven proof skillet with the heart, gizzard, neck and wing tips of the bird, maybe with a little olive oil and butter. I start the browning on the stove top and finish in the oven at about 350. I put everything from the skillet into a sauce pan, every little morsel, deglazing the pan also. Add a whole carrot, an onion, a celery rib, bay leaf, parsley, pepper and garlic cloves and simmer very low for a long time, till gizzard and carrot is very fork tender.
I strain the meat items out, chop what I want for the gravy, discard the rest. Strain the broth and hold until ready to make gravy.
I make the gravy from this and from unsalted chicken broth. I also glean small bits of crusty drippings from the turkey pan corners and add to the gravy before adding any salt.
I do the majority of this early, as I drop the bird in the brine, then refrigerate until the turkey is on the home stretch. You'll be surprised at the quantity and flavor you can coax out of the giblets and wing tips this way.