Migrated to magento 2 a few months ago. Recommended next steps?

Hello, we have migrated to magento 2 a few months ago and have a basic site running, we are working with a developer and I kinda do the marketing and store management. This is our website: https://3dtrcek.com/en/

I have no experience but I would like to start upgrading the website. I guess a good place to start is Homepage, category structure and product page optimization. I think I will focus on these things in the next month or so because we would like to translate the website in 3 more languages. After that I was also thinking about stuff like cross sell features at different stages of the buying process but that seems more like a nice to have and not so urgent.

Since I am not an expert I am wondering are there any other low hanging fruit I should take care of. What would your recommendations as magento experts be? Are there any mistakes or bad decisions I should avoid?