Hi Chris, lovely images you take. First of all, you need more detail in your title and product description. I had no idea what you were selling and had to go and look up your about info. Bear in mind many buyers won’t bother to do that. Talk about the size, print quality etc remember that search engines like Google use the title and the description to find an rank pages so if you want someone to search ‘High quality photographic print landscape autumn’ and find an item of yours then you need to include those words. Keywords only work for the Folksy website. Perhaps a photo of one of your images framed to show people what it would look like on their wall would help too.
As for social media, I reckon Pinterest and Instagram would suit your work best, using hashtags on Instagram is a good way of getting all sorts of people to find your images, and you can pin items from your shop straight to your created board in Pinterest. I have no experience with Twitter so hopefully others will chime in with that. If you have a Facebook account you might want to set up a page too.
Good luck and lots of sales!