The family Thanksgiving gathering is a great time for that project. Folks are cleaned up and spiffed up. And they really will be appreciative of your efforts. So put down your glass of wine for a bit, and get after it. Here are a couple of tips.
For head-and-shoulders portraits I like a focal length of somewhere between 80 and 200 mm. This produces a nice perspective, and also gives the subject some breathing room. Except for my pop-up for an occasional flash of fill-in, I prefer to use ambient light. This photo of one of my grandaughters was taken by the indirect light of a large window. At 170mm my zoom had a maximum aperture of about f5.6, so even at a film speed of 800 the shutter speed was a slow 1/30 sec. But by bracing my elbows on a piece of furniture, and with the help of image stabilization, the image remained sharp. In post-processing (Lightroom) I probably lightened up the shadow side of her face a bit and added a bit of vignetting.The soft light of a fall afternoon is also nice to work with. Here, although we are in some open shade, there is enough light from the background to provide a nice bit of glint on the hair, and an overall feeling of warmth. A focal length of about 100mm was used, at an aperture of f8, thus softening the background a bit. Fill in light was provided by the pop-up flash, with it's output adjusted downward by about a stop. I try to keep the fill-in in balance with the background, which cameras do pretty well on their own, or with some exposure adjustment.
So leave the snacks for a bit and get out your camera this Thanksgiving. Then follow through and have some prints made and framed. The chances are you will come up with some photos that will make good Christmas presents, and perhaps cherished images that will be passed through generations.
A couple of final tips - Be aware of ambient lighting character. You are looking for semi-directional light for modeling features which is also fairly soft. Avoid using flash by taking advantage of your camera's ability to get decent results at fairly high ISO values. And before gathering your subjects, take some test shots to get your exposure down. This will save fiddling while your subjects are impatient to get back to the party.

