Having a disciplinary interview is an unpleasant experience for both you and your boss. Needless to say, you should always strive to perform at a level that will earn you accolades, not rebukes. In the event that you are asked to participate in this process, here are some things you can do:
BEFORE THE INTERVIEW
Prepare yourself thoroughly. You will obviously know the reason for the interview. Collect whatever facts you can, particularly those that may be in your favour.
Prepare mentally. Do not go in looking for a fight. Plan to come out of the process better and wiser. Be prepared to learn and find ways of improving yourself, but also be prepared to defend yourself should the process be unfair.
If you work in a unionized workplace, inform your shop steward of the interview, although the company probably will already have done this. Find out what rights you have or don't have.
Respond to reason, logic, and the facts.
Listen to what is being said. Don't be defensive. Make notes. Ask for clarification and specifics, particularly if your boss uses the words "always" and "never."
Respond unemotionally, as difficult as that may seem. Focus on solutions. If you have difficulty coming up with a solution, ask your boss what he or she would do in your situation.
Don't attack your boss unless you have ample reason to do so. If you do attack, focus on the issue rather than the person. Saying "I am aware of the following situations that have not been dealt with" is better than saying "You play favourites."
Leave the meeting with a clear understanding of what is expected of you and a level of comfort that this can be done. If not, you should get whatever help is available to turn the situation around. This could include additional training or better equipment.