Hi Chris
Lovely items! All nice :)
Here is an Etsy article on how the searching works that may be of interest:
https://www.etsy.com/uk/help/article/34234144469Regarding tags I wouldn't use many up on your name, perhaps in one or two listings only and use the other tags to get found in the search.
Do you plan to roll out other acrylic colours? I'm sure you do, it's early days! Would love to see a pink alphabet coaster.
I would query the postage for overseas, it seems rather steep. You can set up shipping profiles if you haven't already so all the coasters are on the same and if the price later changes you change it in one place and it will change for all listings on it. If the items are really heavy and that's causing the cost then mention that in the shipping policy.
Lastly, I would recommend putting a link back to your shop at the bottom of each listing and another link that's vaguely related to the item in question, like click here to see more coasters: and have a link to the coaster section (when you've set up sections ;))
Lovely stuff, I wish you many sales
Cherry