Most of us have been let go from positions because of circumstances beyond our control or as a direct result of our actions (or inaction). Whatever the reasons for termination, the challenge facing you now is to minimize the damage on your resume, while making it an effective marketing tool.
1. Let the resume format work for you in downplaying a job loss.
Instead of using a reverse-chronological format that accentuates employment dates, use a combination format (part functional, part reverse-chronological) that showcases what you know. The functional area directly below the opening summary would include your skills. For an accountant that would mean account reconciliations, tax returns, internal controls, etc. The fact that these skills were attained at XYZ Company is minimized as employer names are not mentioned until the very end of the resume in a reverse-chronological listing.
2. Use dates of employment to your advantage.
If you were fired from a job of short duration that fell within the same year as your last position, it can be completely excluded. For example -- you worked at ABC Company from March to September of 2008. Before that, you worked at DEF Company from July of 2002 to February of 2008. Simply list the second company (DEF) with the years of employment (2002-2008) -- no months. This will show an unbroken employment record.
3. Never explain on a resume that you were fired.
As much as hiring managers want to be fair and open-minded, they are only human and will tend to dismiss any candidate who admits to being fired. No matter how you try to explain your dismissal (e.g., "It was office politics." "My manager didn't like me; I have no idea why." "It's because I'm old; they wanted someone younger."), the explanation will still sound negative and self-serving.
4. Don't confuse being laid off or let go due to downsizing as being fired.
If your company was bought out by another firm and you were let go, that's not the same as being fired. If your position has been eliminated (for whatever reason), you weren't technically fired. Hiring managers tend to look at "being fired" as a negative that was caused by the employee (e.g., they stole company funds, they were always late to work, they didn't fulfill their daily duties). It's important to note the distinction and to list those jobs on your resume when economic conditions beyond your control were a factor.
5. When there's no way to avoid the fact that you've been fired.
If the industry you're working in is a small one and everyone knows about your job loss, or if the potential employer does a background check on you, then it's essential to showcase the positive (what you achieved at the job), and to minimize the negative (confrontations with management or co-workers). An interview is not the time to prove that you were treated unfairly at the last company -- rather, it's the time to prove to the new company that you can excel because of your unique set of skills and qualifications.
6. How to answer: 'Why were you fired?'
Avoid the negative and accentuate the positive. Never criticize former employers, past management, or colleagues. Always turn the firing into an opportunity that allowed you to seek something better, whether your goal was monetary or one of personal satisfaction. Keep your answer short and stick to it, especially if you're going through multiple interviews within the same company. Your interviewers will compare notes and you don't want them wondering why your story kept changing.