What can I do to enhance my smile? (Photo)

Thank you for your question, your smile arch should be widened, this can be achieved by two procedures. My first recommendation for you case would be visit an orthodontist. Though orthodontic treatment you can achieve a much wider arch and this will give you better lip support and even the airways will have a better passage, which will help even with the darkness under your the eyes. After orthodontic treatment then maybe you will require veneers treatment. One good option for your case will be doing a digital prediction and mockup before starting any. Hope all the best for you.

I suggest you visit a facial dermatologist as there are treatments to change facial muscles. Boutulin shots and fillers can be used to better your smile.