What to write in a thank you note to someone who helped me?

I've been trough a lot in my life and lately its been haunting me a lot + my cousin just died from a 4wheeler accident so i go talk to one of my teachers when ever i have the chance just because I know he'll listen and be there for me. But with Christmas coming i'd really like to give him a thank you note written by me and a gift to show him how much i appreciated it. does anyone have any idea what to put in the note and what i could give him? i thought of maybe i personalized ornament and a hot chocolate set (kind of an inside joke between us) but i really don't know what to give. please help!