How Do You Get Ahead?

Started playing Stellaris a couple weeks ago. After a few wins on Captain difficulty, I bumped it up to Admiral, and it feels like I've hit a brick wall. It takes me about 100 years to even approach parity, by which point the AI has amassed so many resources they can overwhelm me on a military/economic front. I'm obviously doing something wrong, so I have to ask:

How do I overcome the deficit and get active on the map earlier?

My current strategy is

* Explore aggressively. Ideally, I'll be able to cordon off a chunk of unexplored territory so it's protected from other empires' expansion. * Start with Exploration tradition, grab One Vision as first ascension, take Prosperity second, and go from there. * Focus on research once core economy is stable-ish (all positive), since I can't compete in terms of quantity, my military needs to win on quality. * For worlds, Capital remains more or less balanced. First colony is dedicated to mining/alloy production. Second is a tech world to begin pumping research. (Adjusted based on resource deposits, ofc) * For basic resource districts, focus on getting specialization and the +job capacity buildings. * Get clinics/clone vats/robotics ASAP, to kickstart population growth. * Grab Dyson Swarm and Megaforge the moment they're offered, build aggressively. * Put a monument on every world for unity. * Spy on everyone, Improve relations with directly adjacent neighbors. * Offer trade agreements to every empire that'll accept them.