Here are 3 things you could do.
1. Build a website, don't worry about the platform, yet. Just make sure you have some passion or expertise for it. To me the first thing is knowing how content drives traffic.
2. Tag your website with GA, Google Search Console, and Bing webmasters. Bing offers good technical recommendations. If Russian is your thing, Yandex Metrika is great.
3. Get yourself a crawler software, I use Sitebulb, because I think it's easier to use and configure. ScreamingFrog is probably the leader in the industry. Once you have your crawler, get to crawl websites, good websites, known websites, poorly ranked websites and compare them.
4. An extra, SEOs use a lot of technical stuff to sell their services, but at the end of the day if you follow Google's rules and think in the user, you'll be good.
I've been in SEO for over 15 years, and I can tell you that the advancements in the last 3 years made everyone go back and relearn a lot of stuff.