Ways to perform effective keyword research to target the right audience?

I'm Ethan, and I've been into business for some time, have some knowledge about marketing and social media but I really don't get SEO. I want to improve the visibility of my Sellvia store and social media accounts, how can I do it? Are there any apps or tools to help with it? Or do I just hire a specialist? Also Sellvia itself has a SEO pack but idk if it worth it or no...