What have past theologians written about preparing to die?

I have not encountered specific works dedicated to the subject, but certain authors seem to permeate everything they wrote with death in mind. The subject of death permeates in almost everything written by Jonathan Edwards and Martin Luther.

Of all the people I have encountered Jonathan Edwards made me think about my own death more than any other. I was in University when I first encountered his sermons on the flood and Sodom and Gomorrah.  After that time I have probably had at least one wondering thought thought every day about my own death and if I am properly prepared to die.

It is said that Edwards lived a life prepared to die.  Here is some sample snippet that indicates Edwards typical way of arguing:

Be persuaded for your own safety, to look a little forward and be concerned about your welfare an age hence, and not only what you shall eat, and what you shall drink, and wherewithal you shall be clothed for that little time you are to remain here. Frequently ask yourself the question, what you intend to do if death comes and summons you out of the world, and from all your earthly good things. If you are not prepared to die, you cannot resist the summons: none are able to grapple with the king of terrors. When death comes, he will hale you from all your dear enjoyments, whether you will or no, never to set your eye on those things more. And as there will be no encountering death, so neither will there be any entreating it; he'll not be wrought upon by cries and tears; he is altogether inexorable. He'll not wait for you one minute, that you may have a little opportunity to be better fitted and prepared to go with him. Jonathan Edwards Sermons)

Luther also brings up death quite a bit.  He usually is a little more positive about then Edwards and possibly a little more mature about it, but both seem angled in the same direction.  

For example, Luther compares death to childbearing:

“When a woman is in travail she has sorrow; but when she has recovered, she no longer remembers the anguish, since a child is born by her into the world” [John 16:21]. So it is that in dying we must bear this anguish and know that a large mansion and joy will follow [John 14:2]. (Luther's Works Vol 42.100)

Luther sees death as a monster we must face and therefore should think about it often ensuring our faith in forgiveness is greater and when death finally comes, not to think of it any longer but to rely on our sense of forgiveness and think of nothing else, for this will be a day of trail:

Death looms so large and is terrifying because our foolish and fainthearted nature has etched its image too vividly within itself and constantly fixes its gaze on it. Moreover, the devil presses man to look closely at the gruesome mien and image of death to add to his worry, timidity, and despair. Indeed, he conjures up before man’s eyes all the kinds of sudden and terrible death ever seen, heard, or read by man. And then he also slyly suggests the wrath of God with which he [the devil] in days past now and then tormented and destroyed sinners. In that way he fills our foolish human nature with the dread of death while cultivating a love and concern for life, so that burdened with such thoughts man forgets God, flees and abhors death, and thus, in the end, is and remains disobedient to God.

We should familiarize ourselves with death during our lifetime, inviting death into our presence when it is still at a distance and not on the move. At the time of dying, however, this is hazardous and useless, for then death looms large of its own accord. In that hour we must put the thought of death out of mind and refuse to see it, as we shall hear. The power and might of death are rooted in the fearfulness of our nature and in our untimely and undue viewing and contemplating of it. (Luther's Works Vol 42.100)

Luther saw the guilty waving finger of the Devil as like the fiery vipers biting Israel in the desert.  The only cure was too look at Jesus on the cross.  This is the deepest insight into how to face death not being bothered by our sins in the final hour.  He say's you must not be captivated by sin, looking at your own many sins directly, or looking at all the sinners falling into hell.

You must turn your thoughts away from that and look at sin only within the picture of grace. Engrave that picture in yourself with all your power and keep it before your eyes. The picture of grace is nothing else but that of Christ on the cross. ( (Luther's Works Vol 42.104)