Key Skills for Fast SDR to AE Transition: Insights Needed

As I finalize my transition into an SDR role, I'm keen on structuring my first two years for rapid progression. For sales leaders and former SDRs in this channel, what were the 1-2 key skills or certifications you mastered that enabled you to move from SDR to Account Executive (AE) the fastest? Was it product knowledge, or truly mastering cold outreach?