Before having a face to face meeting with a parent(s) there are some things you want to make certain you've done.
1. You have attempted to resolve the issue over the phone. Notice I said phone and not email. Emailing is a losing strategy for anything more than a simple response. The phone is better unless the caller becomes agitated, belittling or threatening.
2.  Have all documentation and make certain you have followed your school/districts policies concerning parent notification and discipline hierarchy schedule.
3. If you've made mistakes, overreacted or just lost your cool with a student, admit it, but don't over-apologize. The student in most cases, did have some responsibility in getting you to that point.
4. Let the parent talk first. Don't think about saying a word until you have let them fully explain and/or vent concerning the issue. Don't be afraid of silence after they have finished. They may not be through and the silence is more frightening to them than to you.
5. Restate what you heard them say and get agreement on the points. 
6. Defend your actions, point by point, using your documentation, school and classroom policies etc.

At this point, if you hear the below comments, the conference is over and you should give your parting greetings and excuse yourself. Here are the typical comments that tell you the conference is over.Give a quick response and dismiss yourself. Don't argue the point. It's over.

1. I'll talk to _____ when they get home tonight. Sorry for their behavior.
2.I don't quite agree, but you're the teacher.
3. You just don't like _(insert child's name here)_.
4.You are just singling _child's name here________ out.
5. You are just prejudiced, a racist, hate (insert race, color, religion, ethnicity, sexual orientation,handicap, learning disablity, here)__ people etc. (This is one comment I don't tolerate. My reply is that if they have proof of this, they need to file an action against me. If not, they need to keep their mouth shut. I teach in an urban school with a variety races religions and sexual orientations. I will not let an idle charge go unchallenged. My day to day existence demands that all parents know that I am fair in regards to all issues of race, religion, handicaps, and sexual orientation.)
6. Profanity in any form be it mild or hard core. No teacher should be subjected to this.