The highest-impact landing page elements to A/B test are: the headline (the first thing visitors read), the CTA button (text, colour, size, and placement), the lead form length (removing fields directly increases completion rate), social proof placement (testimonials or client logos above versus below the fold), and the hero image or video. Test one element at a time and run each test until you reach statistical significance - at minimum 100 conversions per variant. Every landing page should be designed with mobile-first UX principles since the majority of paid traffic in India arrives on smartphones, not desktops.