If everyone knows their job and does it in a spirit cooperation, why should there be conflict? Because it is potentially endemic in all human relationships. Accepting that this is so makes the conflict easier to resolve. But if people listen to and trust one another and work from a basis of shared information and if they are able to give and receive helpful suggestions, they will reasonably expect to resolve conflict.
Knowing where conflict is likely to occur and specific aspects of handling it constructively are necessary skills for everyone. Common sense, fair-mindedness and self-discipline, as well as a belief in 'the free and open sharing of information' and win/win situations, are essential to conflict resolution.
Being able to distinguish between personality conflicts and conflicts over issues helps too. In general, it seems likely that dogmatic authoritarian or low-esteem people are more likely to exhibit conflict behaviour. And some people are honest enough to say they don't like being on teams or committees because they like getting their own way. For such, self-discipline is obviously the way to go when teamwork is unavoidable.
Put-downs are not acceptable in conflict management. 'Why' questions in seeking reasons for someone's behaviour can almost be guaranteed to cause more conflict since they seem to require justification. An already defensive person will quite likely become more defensive. 'What?', 'How' and 'Tell me about it' will elicit more information and cooperation. Seek to develop assertiveness skills and encourage assertiveness in others.
But first, make sure you know exactly what assertiveness is. It is not aggression, though stepping across the line between the two is easy. If your voice is louder than it needs to be, you've probably stepped over! In How to Say What You Mean, written to help people manage difficult situations at work, Norma Michael says you are behaving assertively when you:

• Express your feelings and opinions in a direct honest and appropriate way, without violating someone else's rights
• Repeat what you want even under stress until you are heard

Assertiveness makes it possible for you to feel comfortable about:

• Not avoiding the issue
• Not giving in
• Not engaging in unhealthy competition
• Working with others to achieve the best possible solution

If we were all able to express ourselves with simplicity, clarity and directness, life would be a bed of roses. But things aren't always the way we want them. Here are other conflict management approaches:

• State issues specifically, not in generalised or absolute form. For example, you might say, 'You did that yesterday and the day before' rather than 'You're always doing that'
• Get both or all the parties to define and accept the problem objectively without giving opinions. Encourage them to relate facts only, or describe what has happened
• Involve everybody in finding a solution and make sure it is acceptable to everyone and that it will work. Consider other solutions
• Listen actively to everyone. Discipline your emotions by using your assertiveness skills to respond (this is almost as difficult as overcoming personal prejudice - also an important factor in communication breakdown). Concentrate on what is being said. Request clarification if you don't understand
• Use a circle set-up for discussion. In a one-to-one situation, move away from a seating arrangement that suggests authority of one over the other
• Take your time

from: Project Management by K. Paul