1) First set the AF to one of the "zone" modes and ask them to keep the "orange squares" on your face. Certainly do not use spot or single point. If they are really inept, perhaps even the 61-point automatic slection mode (large "tampon" shaped indicator)
In the latter case the camera typically chooses the closest subject so hopefully you are that object. I personally prefer zone AF I mentioned first in these cases.
2) I think Tv mode might work bettert than even P mode, crank up the shutter speed to a reasonably high level as lighting will allow... with higher shutter speed works with wide open apertures giving you good bokeh and also minimizes the shake issue (get a sense of how fast the shutter speed should be using AV metering first wide open).... Increase ISO as needed to set shutter speed to minimize shake.
3) If lighting is particularly challanging, consider using a flash, if only as a fill. One assumes these are snaps and not studio level portraits in which case you hopefully won't be asking people who can't focus to take the picture.
4) Ask Gomer to take several shots so you get a few good ones