Just because you are quitting your job, that doesn't mean that you can say and do whatever you want. Your history is a part of your present and future.
Is is very important to maintain a good relationship with your past employers and colleagues even if you had conflicts with them. Future employers may contact previous ones to ask about you.
You are not in need of bad reputation. Below are tips on the things that you should/shouldn't do while you are quitting your job.
1) Don't resign in a moment of anger
No decision in life should be taken in hast, under stress, or in a strong emotional state; quitting is no exception. Weight your options carefully and rationally.
2) Don't change your mind easily
If you are that good you may be offered incentives to stay. Don't accept anything offered instantly. Tell your boss that you need time to think even if the incentives are too good. This is negotiation mechanism and will strengthen your position in the company should you choose to stay.
3) Make it official
Make sure to write an official resignation letter, an email, or preferably both. The important thing is that your resignation should be documented and dated.
4) Make it verbal
Even if you have a dispute with your superiors, you need to have enough courage and confidence to confront them and say it with a smiling face: "I resign."
5) Date it
Put a date on your resignation letter. This will mark the number of remaining work days and serves as a notice period. There are countless incidents where the employee and company had a disagreement on when is the last working day due to this tiny mistake.
6) Don't give lectures
Don't give your bosses or colleagues speeches on how things should be done. If you have an improvement idea then you should have said it while you are in position, not after. If you are quitting because you don't like how the work is being done, you can mention it in your resignation letter but not after your resignation has been accepted.
7) You don't have to be honest:
Feel free to keep the true reasons for yourself. You are not obliged the reveal the reasons for your resignation, but don't lie! Being discreet is not the same as lying. Lying is saying something wrong while discreet is the right to remain silent. Having said that, it is recommended to be open your boss and say it frankly.
8) Hide your joy:
Don't tell the whole world before you tell it to your superiors. It is just inappropriate and unprofessional. Hide your joy until you get acknowledgment from your boss.
9) Stay professional:
Many people consider the last days in their job as a holiday. They start arriving late, leave early and barely do anything useful. In their minds they are thinking: "What can they possibly do? Fire me? I already resigned!". Such behaviour is neither professional nor ethical, so don't do it.
10) Clean handover:
Make sure to handover your job to your replacement as complete as possible.