The proper way to resign 

Once you have accepted a new job, consider the timing of your resignation. Since two weeks’ notice is standard, make sure your resignation properly coincides with your start date at the new company.

Try to avoid a delayed start date. Even if your new job begins in 10 weeks, don’t give 10 weeks’ notice. Wait eight weeks and then give two weeks’ notice. This way, you’ll protect yourself in the event that your new company announces a hiring freeze a month before you come on board. By staying at your old job for only two weeks after you’ve resigned, you won’t be subjected to the envy, scorn or feelings of professional impotence that may result from your new role as a lame-duck employee.

Use tact, be direct.
Resign in person, preferably on a Friday afternoon. Ask your supervisor if you can speak with him or her in private and then get right to the point. Say that you’ve enjoyed working there but an opportunity came along that you couldn’t pass up. Make it clear that your decision to leave was made carefully and doesn’t reflect any negative feelings toward the company or the staff.

When you announce your resignation, you should also give your supervisor a letter stating your last date of employment with the company. Keep your letter short, simple and to the point. There’s no need to go into detail about your new job or what led to your decision to leave. If these issues are important to your old employer, he or she will schedule an exit interview for you, at which time you can hash out your differences. Be sure to provide a photocopy of your resignation letter for your company’s personnel file so that the circumstances surrounding your resignation will be well documented for future reference.

Be firm about your decision.
Make it clear that your decision is final. State that you would prefer that the company not make you a counteroffer, since you wouldn’t want your refusal to accept more money to appear as a personal affront.

Save discussion of why you decided to leave for your exit interview, if there is one. If pressed, focus on the fact that you were given an opportunity that you couldn’t pass up rather than the reasons you are resigning.

Offer to help ease the transition.
Finally, ask if there’s anything you can do during the next two weeks, such as help train your successor, tie up loose ends or delegate tasks. An employee’s resignation means that the other staff will have to adjust their workloads, so anything you can do to leave things in order will be appreciated and lessen the negative impact of your resignation.