I often make a point to tell my parents that I love them, and when we part ways, I strive to ensure that the parting is on a positive, loving note, even if we're only going to be apart for a short time.
I do very much the same with the other people I care about--particularly the bit about not parting on a sour note.
I also try to enjoy the time I have with people, when I'm with them, and to be mindful that that time may be limited.
Other than that, I'm not sure what else I could do. Death is something that is often very difficult to prevent, predict, or prepare for, fully.
"Gentlemen, the verdict is guilty, on all ten counts of first-degree stupidity. The penalty phase will now begin."--Divine, "Pink Flamingos."
"The strong rule the weak, and the cunning rule over all." HS!