Start to grow an email list. You can put a sign up form in your store. Then, offer exclusive sales on your website just for email subscribers.
Sign up for a Mail Chimp or Convert Kit account (they are either free or low cost email providers). Once you have some people on your email list, develop an "email drip" to automate your email marketing to them.
I also recommend investing in online advertising, especially social media advertising and content marketing, but you can start an email list for free to get it going as a first step.
I grew my business in the first year by using subscription boxes for cross-marketing. The subscription boxes in my niche already have thousands of eager customers. The boxes source my product just above cost and we get to introduce ourselves to thousands of new potential customers. We don't have to pay; in fact, we generate revenue AND marketing opportunity this way. It's a win-win.
I started my Etsy shop in August 2016 and was a complete newb. By the end of 2017, I had made multiple six figures. My best advice is to do the following:
1. Product photography is one of the most important things you can invest in. Good photos get sales. Mediocre photos get ignored.
2. Learn Etsy SEO. There are a number of resources online that can teach you about this, and invest in Marmalead's keyword software.
3. Encourage customers to write you reviews. It will help your rankings & establish trust.
4. Take advantage of Etsy's holiday sales (i.e., Etsy promoted stores that were offering discounts during the holidays)
5. Establish other revenue streams. Expand beyond Etsy. Set up an eCommerce website and also sign up for Amazon Handmade. (P.S. We make much more on Amazon Handmade as compared to Etsy)
6. Pitch your product to be included in subscription boxes. This is a unique and cost-effective way to get in front of new customers.
I have so many other tips and suggestions but these are the most important/actionable for now. Feel free to give me a follow up call if you want more details on any of this. Thanks!