1. What is your friend's favorite animal? If it's not a horse, drawing their favorite would be a more personal touch.
2. What kind of art style are you comfortable with? Rearing horses can be challenging, especially if you're not experienced with animal anatomy.
3. What is your friend's taste in art? Do they prefer realistic, stylized, or cartoonish drawings?
Once I know these details, I can give you a better recommendation!