Follow these steps gingerly:

1. Review the organizations policy on letters of reference. Remember many organizations don’t have a policy so this may be left to the discretion of the manager. You should attempt to get reference letters from people in the organization with whom you have had good relationship.
2. Inquire from your manager if the letter would be favorable. There have been instances where managers forwarded detrimental information to a perspective employer.
3. Ask you manager if the organization provides dates of service. If not, check your own records to be sure you have the correct dates on your resume. Remember job hopping is considered  questionable by perspective employers. Most employers like to see at least 3-5 years per work experience, if possible. There could be  extenuating circumstances that you should be prepared to share during an interview.
4. Seek feedback from your current manager. They may provide you with some helpful tips for your future success , even though they may not provide you with a written or formal reference.
5. Don’t be confrontational. You should be sure to end, if possible,  on a positive note . This is a very important point even if you have had some difficulties with the organization.
6. Always  provide two weeks notice.
7. Be sure to return your I.D. badge, computer and all other company property as instructed and within their time-frames.
8. Provide thank-you notes to all persons that have been helpful and instrumental in your development at that organization.
9. Be sure to clean your work area and secure all confidential files and information.
10. Take a deep breath and move forward to your next job venture with a “Spirit of Excellence.” Don’t let depression and hostility harbor in your heart.