data collection

When I go to update the IEP goals/objectives for my students each trimester, I never feel like I have enough concrete data to be able to accurately evaluate the student’s progress on a particular objective. Please share ideas, forms, methods for collecting data on IEP objectives. I would like to know how often you collect data, your system for collecting it, the staff involved in collecting it, and any other details that will help me be thorough, yet efficient, with this overwhelming task. Also, please share any clues in [i]writing[/i] the objectives that makes the data collection easier.