Played many 4x games, longtime Civ4/5 fan especially, aside from many RTS etc...
Dicked around my first couple games and invariably fell behind, until I played my most recent game, after some cursory reading on game mechanics.
I played the fascist human premade race, on a small map with as many civs would fit and no advanced starters.
I kept my science vessel active scouting everything I could, focused on building mining sites and upgrading buildings on my homeworld towards minerals and energy credits to keep a healthy economy rolling.
Research was basically Relevant Epic options>fleet upgrades>relevant tile blockers to my planets>* with the exception that colony ship must be rushed asap.
By the time I was starting to make contact with neighbors and figure out the political dynamics around me, I was on my way to 2, then 3, then 4 core worlds, which I split into my homeworld being high energy focus plus my military production facility, 2 science worlds of medium size and one mineral world of very large size and 100% habitation.
This gave me a stable economy and a basis to start adding spacestations to my other planets to increase my pop, increase my borders, fill out all remaining mining/science slots, and begin building the largest strongest fleet I could.
Once I was strong enough to turn one neighbor into a vassal, I repair/upgraded my fleet, replenished any missing craft and moved on to the next. One by one, the remaining empires around the galaxy fell to me, and each assisted me in the fall of the next.
I'd like to play a mostly scientific game at some point, akin to Korea in Civ4/5 where they do best as a small pop focusing on high tech and outpace others.