Etsy and Google use very different search algorithms. It is sometimes difficult to grasp trying to optimize for both Etsy and Google. Learning what they share and do not share can be the key to being found in both places. Do your best to optimize for both.
They both give weight to the title of your item. Etsy gives strong emphasis on the first three words of your title. Google gives a little weight to your entire title. Put the most important words first.
Etsy gives heavy weight on tags, Google all but ignores them. Using multiple keyword phrases is good for tags on Etsy. Repeating the same word on different tags is good because the Etsy search algorithm is looking for EXACT keyword matches. For example if you have a vintage red leather belt, try to think of ways people would search for it. "vintage leather" and "vintage belt" both describe the item and optimize you for two different phrases. Avoid tag stuffing. If you have a belt that is three colors "red orange blue" is not a way to describe it. You'll want to use the colors in separate tags like "red belt" and "orange leather" and "blue buckle".
Etsy does not use the description in their algorithm but Google uses it very heavily. Try to make sure that you have the keyword phrases listed in your description. Try to use them multiple times as long as you can make it sound conversational or descriptive without sounding too repetitive. I try to use the keyword phrases twice in the description and have some of my other keyword phrases spread out in the description since Google does not look at tags. Please note that since your tags are listed in the main body of your description it is possible that Google does see and use your tags slightly.
There are a lot more factors and variables that go into both search algorithms but I feel like these are the main ones that you have control over. Make your words count. Etsy and Google do not release all of what goes into their search algorithms so we may never know exactly whet they look for but taking steps to optimize for what we do know they are looking for will at least give us a better chance of being found.