I'm heavy into economy throughout any given match, and having a strong economy in Sins also means you typically can have a pretty powerful military in the mid-late game, but you're weak for rushes early-mid match, so you've got a bad Achilles Heel when that's your focus.
It works for me though, because if you're smart about it you can turtle for a while, while your economy bubble builds up.
The way to do it is to have a very small initial fleet that is all about fast and efficient expansion, that can take early game unoccupied worlds very quickly, that you can then bolster with upgrades that will boost your economy, like better population centers. This small fleet means you're not really going to be able to defend yourself outside of tactical structures like MAC/Hangers/Patrol Stations, and so when you're on the defense (which you will be) you need to be focusing partially on turtle-ling either some of your inner colonies so you don't get completely swept over, or building a good external defense line on some of your key boarder worlds where you can push an enemy to attack you at.
Basically, don't get any fleet upgrade until you hit the point where you absolutely need a fleet, because fleet supply upgrades (not capital ship slots, but fleet supply specifically) eat away at your economy, as there's a meta surrounding it where you now have to actually monetarily and resource-wise supply your fleet. At later upgrades you might be eating away 50 - 70% of your potential economy just to have a larger fleet, and you might not actually need that larger fleet because you're just focusing on tech early game, unless you're being rushed.
Pushing the civilian tech tree forward, building trade stations, resource extractors, upgrading your planet population upgrades, and making sure every planet has a resource boost structure like a Springhill helps massively push your economy upwards. By the time you're entering the end game your enemies may be spending everything they have to fight you, while you have strong defenses that they can't push through, and you can pump ships out that are fully upgraded because you've had the resources to upgrade a build ships the whole match.
This strategy works for me pretty well, but as I said before, it leaves you weak early - mid match, and you can definitely get trashed by even moderately sized fleets if you're not ready, because you really don't have a major force to defend yourself until late game.