my personal tactics generally.
i am heavy on economy, but this tactic can be a little risky if i dont spend enough on military and leaves me vulnerable, but so far this has paid of so well later on in the game.
basically my aim is thinking long term. so get as high an income as i can asap, THEN start researching for your army.
get 2-4 scouts to, well, scout, asap!
rush to get a cap ship and 2 colonizers, then max out frigates. fast expand getting my cap ship on its own, and frigates attacking other planets (so two groups of ships taking planets). build 2 civic research buildings. at each planet max out population.
i usually get all the extractor upgrades, planet upgrades (depending on what planets i have), trade ports on ALL planets i have, and broadcast tower. i do all that with 4 or 5 civics before i even get one military research tower!
i find i don't need to increase my fleet supply above one research until i have finished my civic researching as i start to gather my army.
don't leave your broadcast communication tower until the end, advent have an advantage in culture, USE IT! it increases your income at planets and extractor income, and helps your units fight better which DOES HELP.
in so many of my games i never need to buy tactical structures, only the occasional hanger bay to stop those singular krosov frigates. but dont underestimate starbases, if there is a choke point in which beyond is the enemies land, it can help to put one there until you have built up a huge army to stomp your enemy(s).
i find having variety in my army can be good. but when it comes to advent, GET DRONE HOSTS! they do cost allot, and take up 20 fleet supply! but they are so so so so worth it. BUT some capital ships have abilities which target strike craft, such as flak burst and telekinetic push, so again, don't rely on the strike craft, don't learn the hard way as i have.
i hope this helps, i could write more but then it will start to get tedious. besides, you can only remember so much. i hope there are people who disagree with me, its good to hear variety of opinions.