There is no single answer. The reality is we all discover interesting ways to "save" or "stir" memories in our loved ones. Music is powerful, of course; it often triggers memory and emotion. Additionally, photographs help with memories. Prepare photo albums that are labelled with names of family and friends, especially of those who visit.
With regard to saving memory or providing cues for everyday tasks, post-it notes with short, to-the-point instructions help.
Use what you know - items of comfort tend to revive memory.