Assume that means a hearing with statements and evidence? I would go through everything you possibly have that could be evidence, print it all out and file it in a big folder, separated into topic categories. Then go through all of those and narrow it down to a few really strong pieces of evidence. Maybe 9 or 10 pieces - that back up any arguments you want to make or anything you want to prove something. Go through those with a highlighter pen (not too much!) to highlight a specific line you want to draw attention to and maybe write the odd annotation comment in the margin. This is mainly to help you construct an argument, but also so your barrister can construct an argument based around the evidence.
Also dig out any other documents that might help with evidence - letters or emails to and from school, GP, or any other authority.
Rule of thumb: If anything is not in your favour - leave it out. So if an email includes one thing in your favour, but one thing that throws a spanner in the works or makes people ask questions and detracts from your argument, then leave that one out.
