The most common SEO mistakes can harm your website's rankings. Ignoring keyword research is one major mistake. You should always use relevant keywords that match user intent. Overloading content with keywords, known as keyword stuffing, is another error. Failing to optimize meta titles and descriptions can hurt your click-through rates. You should avoid using duplicate content, as it confuses search engines. Slow website speed is a critical mistake that affects user experience. Neglecting mobile optimization can also cost you traffic. You should regularly fix broken links to maintain site health. Consistently monitoring and improving your SEO avoids these mistakes.