To use free SEO tools, start by identifying the task you need help with. There are free tools for keyword research, backlink analysis, and site audits. For keyword research, tools like Ubersuggest and Google Keyword Planner allow you to find keyword ideas and search volumes. For backlink analysis, tools like Uplink and SEOquake provide insights into your backlink profile. Use website audit tools like Google Search Console to check your site's health. Although free tools may have limitations compared to paid ones, they can still provide valuable insights and help improve your SEO efforts.