Some effective site speed optimization techniques include optimizing hosting (consider dedicated hosting or virtual private server hosting), assessing current website speed using tools like Google PageSpeed Insights and GTmetrix, optimizing images by compressing and resizing them, using caching strategies (browser level caching and server-side caching), optimizing code, making regular updates, and using the latest PHP version. Streamlining themes and plugins, reducing redirects, and enabling asynchronous loading for CSS and JavaScript elements also help improve website performance.