Appraisal review board protest hearing

I need your advice for my upcoming appraisal review board protest hearing.

Last August, I bought a house with my brother. My brother co-signed because I don't make enough to buy a house on my own. But I pay all the mortgages and everything. Both my name and my brother name are on the loan. My brother is married and he lives at another county.

I applied homestead exemption a few months ago and I received that I will only get 50%. So I appealed and received a notice to attend the protest hearing.

How can I prepare for the protest hearing? What usually happen during the hearing? What evidence do I need to provide? Thank you.