Alt tags provide image descriptions to search engine crawlers, which help them to index an images accordingly, so having empty or missingalts is a negative
Schema markup enhances the description of your page by providing metadata and allows for the page to stand out on SERP's because of the rich snippets it provides
When you link out to relatable domains, search engines understand your topic better and helps to increase trust and quality of your web page vital to the success of your SEO