I work in long-term care; any time I'm taking care of people I haven't cared for before I always enter the room and at least shake their hand, smile, introduce myself, and tell them who I am and what I will be doing. I usually do this a few times until they are accustomed to seeing me. For those who have dementia or who are simply forgetful, I knock and tell them who I am again. It's common courtesy to me.

Tammy, via ajnoffthecharts.com