To join some new place, we enter stage carefully, politely; shy like guests, eager to be accepted, knowing that there is no second chance to make a first impression. We do the needed steps at our best to show our best. It is, unknowingly, a rite of threshold passage; a newcomer, “separated” from somewhere else, still “an outsider”, who petitions to become “like us”.
There is good reason to do the same effort when you leave. This comes not always natural and some think that it does not matter any more. But it does. There is no second chance for a last impression either and you can be lastingly damaged while leaving.
Time comes, inevitably, when things end. You move, you quit, you are dismissed, a term consumed, the place closed down. Or you found something better. Change.
Ending good times is hugged and kissed with beautiful sadness and risen toasts; but when the heart is heavy and unsatisfied, in unfriendly climate, with a powerless sense of loss, quality parting is less natural... Separation, like divorce, is hard, often a life-crisis. The centrifugal forces are at work towards nowhere-land. You are about to cross the divide between those who are inside and those who are outside. Partir, c'est mourir un peu...
You feel the instinctive urge to break quickly, abruptly. Better a fearful end than endless fear. The instinct is to "fight or flight” . Just turn away and go, with a snap at those who come too close. Or slam the door to let steam off and make people hear. Some, who did not treat you right, do not deserve anything else. Their unfinished business will not be yours any more.
In fact, if your deliberate choice is to be remembered no matter how, you can use the old Zeigarnik  effect - suddenly suspending everything in mid-air and walking out by surprise; or, if it is your justified interest to do it, not just bad mood, you can prepare a “Parthian shot”  – a compelling and punishing problem you let loose while you depart, a poisoned legacy you unveil or leave quietly in your stead. This is what you do if you do not care for parting well done.
Behave instead as well as when you came. Finish in style. Even with bad feelings you have good reasons to do the right steps of separation, wisely.
Departure well done is a framework that protects you from being impaired while you leave. Do not botch the rite of separation  which must be carried out to close the doors behind you and free your hands, your soul, for new life.
- First of all, part properly because your self-respect needs to behave constantly as who you are; a gentleman is a gentleman even in the gutter. The way you “loose” speaks very loudly, to other people but also to you. It is in the difficult moments that people find out who you really are. You too. You have no excuse to say "I do as they deserve". No, you do as you deserve.
- Second, you are made of what you do, your well-being and view of the world are built of your events assimilated and nothing will delete a mean souvenir. You may not realise now, but you will live your memories repeatedly, and they are all you keep - they will stay with you, want it or not. Bitter things said and done, necessary things not done, farewells failed, unfinished business that does not rest in peace, will weigh unconsciously in your bag like lingering ghosts. Don't poison your blood.
- Third, the sages teach us " Do not spit in the well, you may need to drink from it, again..." It is not the end of the World just of this little world. The future is weaving threads of surprise, where you meet enemies again in narrow streets, and need good will from those who do not count today.
The elements of proper parting: conclude, signify the close, take farewell
Dress well for the last days if common sense allows it; a white shirt and dark tie, the right robe that fits you, signal well that you count at the burial. In fact your tie tells quietly that this is a burial.
Accept that this is a serious situation. Denial is worsening things. Do not pretend to be cheerful.
When several people leave, there is often an embarrassed climate of disunion, each one for himself, live and let die; do not indulge in this. Do not be natural! Smile with solidarity, encourage, offer sympathy. Say 'us" for a last time, if you can. Instead of picking on each other like rats crowded, you can chose to support each-other or to pick together on one deserving to be bitten.
Tour one-by-one the people you know, with a good word for each, careful not to omit someone who does not deserve neglect. As you speak, say goodbye with your eyes, looking in people's eyes, not sideways. Confirm identities and roles, the same way you bowed respectfully when you arrived; call people by their name, say their titles, flatter them with their merits and power, if your stomach allows it. You should confirm identity and respect due, even when you fire someone or especially then.
Exchange little gifts, souvenirs; imperishable solid little nothings for those you want to remember you and nice perishable little nothings for the others.
Signal "keeping in touch" Exchange addresses and phone numbers, as useless as they seem to you now.
Give hints that you will give good reference in the future, if that is possible and with care not to be abused. Make to others a small gift of courage; remind that the journey continues.
Do not accept exit interviews - that is final insult and manipulation - but give exit feedback, good and also hostile criticism - with due care not to have it used against you. Do not document facts, just interpretation.
Create some form of ceremony. A modest event, symbolic sacrifice offered, is an essential signpost when you end things, a full stop that frees you to go. Sit down, eat and drink together, it is a strong symbol. Propose a last supper or picnic or toast even when you feel betrayed. If you are inspired offer a last word. Some last words last.
Say a prayer if you are a believer or something similar if you believe something else. Let the stupid see this as ridiculous.
I remember myself very angry, but offering a mirror-like salute to my colleagues-to-leave in a company where I met some ugly people who hurt me; I mailed a message “to all” - to thank for all they have done for me and wish them: "May all your dreams come true!" This was not so nice, as quite a few dreams are nightmares, reflecting who we are and what we fear and deserve.
Socrates would tell adieu to the crowd that voted him to drink the hemlock:
"The hour of departure has arrived, and we go our ways - I to die, and you to live. Which is better, God only knows." 
Of course, you may choose in some deserved cases, the loudest critique, that of silence.
To end a time in which you invested your soul sacrifice something symbolic; you must pay the ferryman. Then, wash your hands.
The Russians have a custom to sit down for a moment, quietly, to think. Sit down for a last time before you go.
Finally, there is life after life: call soon some people you appreciate and say something nice. This is valuable, as they, like you, feel that they are already forgotten. One of the worst things you can do is not to recognise them when you meet or change the way you treat them because they are no more "in". Let false friends behave like that.
To a moment of uncertainty and ugliness you can bring a touch of beauty and hope. A gentleman is a gentleman even in the gutter.
 Cannon, W. B. (1932). The wisdom of the body. New York: Norton.
 Zeigarnik, Bluma, "Über das Behalten von erledigten und unerledigten Handlungen," ( On finished and unfinished tasks), Psychologische Forschung, 1927 9 (1), 1 - 85.
 Parthian shot, often simplified by current language to “parting shot”: The Parthian warriors of old introduced this tactic – taken over by most mounted archers – to feign running away in defeat and then, while fleeing, turn on their adversary with an unexpected volley of deadly arrows.
 Some classic books explain the theory behind my simple advice: A. Van Gennep, Les Rites de Passage, Paris, 1909 and Mircea Eliade, Rites and Symbols of Initiation – The Mysteries of Birth and Rebirth, Spring, Woodstock, 1995
 [Plato, Apology, Tr. Benjamin Jovett]