Any experience in taming/building trust in a cat?

I hope you keep him, thanks for caring. There are no real tips. it is all basically time and patience. Don't approach him too much right now, let him approach you. it is ok to free feed him eventually but for now i would pick up food when he is done eating and let him come to you for food. Talk in soothing voices. Your cat interprets your body language and the tone of your voice