A few practical things that make a real difference:
1. Page speed. Compress images (WebP), use a caching plugin if on WordPress, and pick decent hosting. Google's PageSpeed Insights and GTmetrix will show you exactly what's slow.
2. Mobile usability. Most traffic is mobile now, so test your site on an actual phone, not just by resizing a browser window.
3. Search Console. Free, and it's the most useful tool for visibility specifically — it shows which queries bring people to your site, which pages are indexed, and any crawl errors Google hit.
4. Content structure. Clear headings (H1/H2), short paragraphs, and answering the actual question a visitor searched for tend to outperform keyword-stuffed pages. Google's algorithm favors genuinely useful content over technical tricks.
5. Internal linking. Link related pages to each other naturally within your content. It helps both users and search engines understand your site structure.
6. Backlinks still matter, but quality over quantity — a few links from relevant, active sites help more than many links from unrelated or spammy ones.
Search Console + PageSpeed Insights are the two free tools I'd start with, since they tell you exactly what to fix rather than guessing.