Stick to truth
Don't lie. Even if you dodge the fact that you were dismissed, the truth comes to light when the potential employer checks references and for not sharing this information you may be denied the job. In the interview discuss the issue briefly and try to explain what you have learnt from the experience and refer to your accomplishments. Of course, dwell on what could be your contribution to the new company.
If you have been dismissed by the new management and could not work with the new boss, accept the fact. Then talk about your relationship with other supervisors and colleagues. You can politely explain the situation saying that you and your new boss have different styles of working and there was a personality clash. Whatever you say, don't wash the dirty linen; if you do that you look bad. Have a list of supervisors and colleagues who can put in a good word. Many people might have faced bad bosses in their career and they could understand your problem.
Your attitude and strategy change
Don't hesitate to explain that there was a change in the company strategy and you could not agree with it and say what you have learnt from that situation. You may say, “After the change in management, my new boss had a strategy in mind for our product range and I thought it wouldn't work. Later I realized that I should have made an effort to understand the rationale behind his strategy and supported it.” Don't blame the company for not accepting your stand. Show that now you are willing to mend your ways to see reason behind the change.
Shortage of skills
May be it is time to acquire new skills to keep your position secure. If you haven't taken to new technology, take a break and fill the gap. You may take the help of industry associations that offer courses and workshops to update skills. Or change your line. You may learn web writing or update your management skills. Sell your new skills to prospective employers by showing how you could add value to their business.
Pull up your socks, if you get a series of poor performance reviews and know why. Be courageous to call your old boss and seek his advice. Or meet one or two of your old colleagues and ask them how you could improve your performance. Keep your mind open and listen to them. At no stage defend yourself.
Have you made repeated mistakes? Aren't your reports thorough? Have you faltered in your assignments? Seriously think what you could do to improve yourself. May be your job isn't fit for you. Then make sincere efforts to change your line and see whether you can make a mark.
If you have lost your job for reasons like misusing company funds, sexual harassment, falsifying company information, no company will accept you. Be honest whatever the reason is. Say only what you have to say. Speak about what you have learnt and how you have changed. Only speak of positive aspects of your performance and achievements.
Get references from your supervisors and colleagues who will give you a positive review. Besides two or three business references, it is better to have a couple of personal references.