Search engine optimisation or SEO for short is refers to any activity that is specifically carried out with the sole intent of improving the online visibility of a website or individual pages of a site. More info on this here;
SEO Gold Coast Is A Local Search Engine Optimisation Expert

Activities that you can undertake to improve your site’s searchability that won’t upset The Goog would be;

  • On-page SEO tweaks such as the title of the page, the URL extension, meta title and description etc
  • Updating content
  • Adding content to an existing page
  • Interlinking (adding a link from one page of a website to another page of the same website)
  • Improving the load speed of the website (as load speed is now part of The Goog’s algorithm)
  • Making sure that every page of your site can be read easily on a mobile device. Don’t concentrate only on your home page. The whole site needs to be search engine friendly
  • making sure there are no broken links, all your forms work correctly and eliminating any other technical errors
  • ensuring that your website passes the 3 second rule test. When someone arrives on your site, is it immediately clear what you do? If the visitor is at all unsure, they will leave in a heartbeat.

Activities that will definitely upset The Goog include;

  • Buying links
  • Spamming your Google My Business (GMB) listing with keywords instead of just your Brand Name
  • Private Blog Network (PBN) links – if they find your PBN’s they will index them

Search Engine Optimisation Today

The art or science of Search Engine Optimisation is really no different today than it was 10 years ago. Sure a lot has changed. But the essential elements of SEO are really what they always were. And that is find out what people are searching for in your niche (keyword research), have a look at who is ranking for those terms and write quality engaging content that is better than your competitors. You can promote that content via social media, do pay per click and/or build links to it (remember that this is against The Goog’s terms of service)

My other advice would be to do everything in moderation and be patient. It takes longer to rank in 2019 than it did in 2009 but just because you don’t see results straight away don’t be tempted to rush in a build a stack of links very quickly as this could backfire on you. If you are not patient you probably shouldn’t be in the SEO game.