Bless you. I have seen firsthand that some people seem to have a knack for working with this part of the population. How wonderful that you are willing to share your talents. I know it will be appreciated by many.
I recently lost my mom after nine years of her living in a facility for patients with Alzheimers. I was very lucky in that she never went through a personality change and never lost her "social skills." By that, I mean she would always smile when "meeting" someone, or when someone directed something to her.
Sometimes just holding someone's hand is beneficial, or just sitting by someone and making an attempt to understand, if they are speaking "gibberish." I always found this extremely difficult to do as you feel so helpless that you cannot make out what the person is trying to communicate, and yet the person is making such an effort. Often, the best I could do were some smiles and nods, and holding her hand.
Often you can redirect the person. Just start talking about something that is going on around the person in the room, or share something about yourself that might somehow relate to the situation...or not. Sometimes it doesn't really matter, as far as anyone can tell, anyway.
Thank you for volunteering. Someone's daughter or son will appreciate you very much.