Know the different web technologies: the first step in any optimization is to know what technology is generating the HTML, if it is compatible with search engine robots and the applicable solutions in each case.
Correctly interpret HTML: knowing HTML is vital for most SEO profiles, but even more so if they are in charge of technical supervision. They should have no problem understanding the different tags that search engine robots use to calculate the relevance of content.
Identify the JavaScript code: although it is not essential to know how to program JavaScript, it is important to identify it and know the main problems it can cause when loading a site, such as rendering blocks.
Properly generate JSON-LD scripts: It is also important to have a certain facility to read and generate the scripts used to define structured data, since in many sectors the rich results are based on these to display more attractive SERPs.
Know the complete process of loading and rendering a website: to optimize this process it is important to know all its peculiarities and technologies involved.
Know the latest WPO techniques: technology is constantly evolving, so every so often new techniques appear to optimize speed. If we want a site to have optimal and up-to-date SEO, it must use the latest techniques.
Know the technical characteristics of the most popular CMS: both those used to generate content (blogs, media, etc.) and those used for e-commerce. A good technical SEO must know the peculiarities of CMS like WordPress, Prestashop or Magento and how to solve their main performance problems.
The main SEO crawling tools: It is important to know all the possibilities of the main SEO tools dedicated to simulating crawling such as Screaming Frog, Sistrix Optimizer or SEMRush site audit. These tools make it easy to spot bugs that will ultimately need to be checked by a technical SEO consultant before recommending possible solutions.