well I would actualy suggest talk to a few teens that have the disease, and find out how they would feel most comfortable with it, you can find them at hospitals alot, just explain to the nurses what you are trying to do and they will help you. as for font, try using different ones on a test paper, there are alot of cool fons now, and if you need help finding some, let me know, I have over 500 on mine
and a couple of artistic style drawings would be cool on it, but make sure it is ot overly down, the less graphic the more eye catching in black and white, and the color go for something that is not to eon in color, as this cold cause an eptileptic seizure in some because of the contrasting colors, sorry if this is not too helpful, but give it a shot, the color i would suggest would be a pastel blue or violet, more calming and less striking in color