Did my supervisors make any comments indicating bias?
If your supervisor made racist or sexist jokes, said they thought you were too old or your disability made you unable to do the job, required you to work on religious holidays, or made other comments that would indicate a bias, you may have direct evidence of discrimination.
Was I treated differently than others in the same situation?
If you don't have direct evidence of discrimination, you may be able demonstrate you were treated differently than those of a different race, sex, religion, national origin, age, or other protected status under the same circumstances. Try to think of people who are of a different race/age/sex, etc. and were treated differently from you. Find out if there are people who have also been the victims of similar discrimination. Remember, just because you were treated unfairly, that doesn't prove discrimination.
Why was I really fired?
Most employees have a pretty good idea why they were fired. If you made a worker's compensation claim and were fired a week later, that's a good indication you were fired in retaliation for making the claim. If you reported your supervisor for Medicare fraud, and then the supervisor fires you, you may have a whistleblower claim.
Is my employer saying something false about me?
If potential employers tell you are going to be hired if your references check out, and then the job is mysteriously filled when you call back, your employer may be giving false or damaging information about you. There are professional reference-checking companies who will call for you and see what an employer is saying about you. If you can prove it's false, you may be able to sue for defamation.
Am I in some protected category?
If you were fired after you took some protected action, you may be able to sue for retaliation. Think about whether you recently made a worker's compensation claim, performed jury duty, served in the military, took family/medical leave, served as a witness in a lawsuit, provided testimony or evidence to EEOC, refused to participate in illegal activity, reported illegal activity, or engaged in protected free speech.
If you believe something illegal has happened, contact an attorney to discuss the possibility that you may have a case.
What if I don't think something illegal happened?
Even if nothing illegal happened, many employers will discuss a severance agreement with an employment attorney hired to negotiate with them. As an attorney who has been practicing since 1986 in employment law, I find that sometimes an amicable transition is the best way for both employer and employee to move on in a positive direction. If you are offered a severance package, it is best to have an attorney review it prior to signing. Many employment attorneys will work to negotiate a better package for you.
The best course of action when terminated, particularly where you believe there was no just cause, is to contact an attorney who handles employment law to discuss your options.