I've been in the same situation when I started my first website. On-page SEO can be tricky for a beginner and it's easy to get lost, when you can only see the results of your work months later. I would advise you to install the Yoast SEO plugin - it's by far the best on-page SEO tool, in my opinion - and follow the instructions that the plugin lays out. If you want to take your knowledge a bit further, you can follow popular SEO entrepreneurs and companies on YouTube. I've found a ton of useful videos there and I can safely recommend Ahrefs, Backlinko and Neil Patel's YouTube channels.