The key to a successful IEP meeting is being ready. Usually, IEPs fall apart for three main reasons:
Emotion before reason
Parents of special needs children are usually aching for their child. So, by the time they get to the IEP meeting, they are already emotionally vulnerable. Try not to let your exhaustion, fears or sadness control your reason, open-mindedness and creative problem-solving capabilities.
Ignorant of options
Some IEP teams need to make a decision on the spot. Therefore, do your best to know what the possible resolutions may include, in advance. Ask around, gather information and request necessary documents ahead of time.
Lack of preparation
If you have a realistic vision about what lies ahead for your child, you will know what questions you need to ask well before the next major decision becomes necessary. Thus, you will want to ask for data collection and responses to your questions or concerns systematically, over the months prior to your meeting, so that you know what to ask for and what to expect when the time comes.
In short, be calm, be informed and be prepared. Maintain your composure, and, armed with data, bring reasonable expectations to the table.