There are a couple important things you can do to drive business to an Etsy shop.
The first is getting a handle on SEO. You need to word and tag your listings just right for the people who are searching for your product to find YOU. There is so much to learn about that alone, you could make a full time job of it. I have only seen the tip of the iceberg with this one, myself.
The other thing I strongly recommend is joining an Etsy team or two. The teams you choose need to be a good fit for you. Etsy is a huge marketplace, but it's also a community. Joining a team creates a smaller circle of influence, and it's been reported that many times sales occur between team members. You're looking for a hand painted vase, so naturally you look at your team members' shops first - and the same is true when your team members are looking for what you provide. This is why it's so important to choose an appropriate team. A slick, lots-of-treasuries type team may look appealing, but when everyone is so busy self-promoting, they may not be your best bet long term.
As for your specific shop idea, I could see it running well on a "Customs" basis. For example, I'm really into fancy goldfish. I have specifically looked for counted cross stitch patterns online, but there are few options that I like. People looking for very specific things may be interested in commissioning you to do a custom pattern, perhaps even from a photograph they have.
Good luck and have fun if you decide to go ahead with it!