The site was really great! It was easy to navigate and I understood everything! You really make me wanna buy one.
These are some ideas I had. Feel free to use them but I will understand if you don't want to. Why not have a page of quotes. These can be quotes about animals in general, pets, and horses. Some can be about freedom, and friendship. Offer something where the person can have a quote at the bottom of the painting or drawing :)
On the pages you show some of your drawings, maybe you could tell people why you draw like that and what you are trying to show with those kinds of drawings. Example: Coloured paintings-Trying to show colour and brightness.
Maybe you could put the paragraph in Custom Portraits, onto the home page, because that really tells people what they are looking at and most people don't want tor look through. They will look at the home page, read whatever is there and if it's interesting, they continue, if it isn't they don't.
These are just a few ideas I had. Overall the website was amazing!