…or do I need to hire a professional SEO?

Both and neither! Keeping up with Google’s (and Bing’s) constantly changing organic search algorithm is an arduous task that keeps full-time SEO agencies busy.
Google Through the Years
It is very difficult, albeit not impossible, to maintain an optimized website that covers the different categories –

    • Website content optimization (i.e keyword density and placement, phrasing, images, meta)
    • Technical SEO (i.e coding clarity, speed, sitemaps, GSC, semantic markup)
    • Link Growth (i.e gaining quality links from related websites back to yours)
    • “The Conversation” (i.e social media brand mentions, conversations, and connections)

Some areas also span multiple categories, such as the increasingly important role of responsive design (mobile friendliness), UX principles (easy to use website, put simply).

The items mentioned above are by no means an exhaustive list, and meant to show a glimpse in to learning SEO.
It is not necessary to rely exclusively on an SEO professional. Usually, the best approach is to find an SEO who emphasizes the importance of education. Your SEO consultant will help you through the important tasks, giving you guidance, training, and implementing solutions that you choose not to take on yourself.

“SEOs can not do high-quality work without you”

SEOs can not do high-quality work without you, as you understand your company and its target audience best. Your SEO will require your time, even if they are doing all of the implementation work, to explain and guide you through how your other marketing efforts impact SEO. They will also need your feedback on keyword research.

All that being said, SEO is not a magic mystery. If you have the time, you can absolutely figure it out! How much work you need to do to gain organic search visibility completely depends on your competition.

If you want to learn more about SEO, here is a beginners guide, and here is a different one just for kicks.