However, I often end up having to shore up my consumer good deficit if I want to pivot into military production after that. For example: getting the first farming tech means I can have ~15% fewer farmers, who can then work alloys. My reasoning is that more research = more resources. I go for a research lab first building instead of an alloy plant. Plus, it'll be hard to exploit my conquests without robots if the habitability doesn't match. This takes up alloys, but I feel that this extra pop growth is very important even when fighting early. I go for a robot assembly plant ASAP on each of my planets. This isn't really based on anything other than a 'militarist = good for aggression' gut feeling.

I often either sport technocracy or meritocracy in addition to DA.

I play CoM - inspired builds, often with a more materialist spin. I have written down a couple of things that might be leading to this, is there anything among this that is a very obvious misplay? Even 'winning' combats seems difficult: I often narrowly lose engagements where I have a smallish fleet power edge, my outiftting counters theirs and I have militarist and distinguished admiralty bonuses (or I win them, yet gain more war exhaustion than they do).

Grinding out the enemy is hard: by the time my economy can comfortably outlast theirs, they will have found an ally. It's hard finding good fleet engagements: guides I've used recommend luring the enemy onto your bastions to cripple their fleet, but the AI is either too smart or too stupid to ever take my bait. I have tried starting out more aggressively a couple of times, but I always hit a roadblock in the first war. It's fun being one of the smallest, yet most powerful empires that imposes its ideology on the universe through liberation wars and GC politicking, but it does make for a pretty boring early game and often feels like playing the 'easy version' of the game (like picking Babylon in Civ). I've mainly rolled into Stellaris as an alternative to Vicky III, so you probably see where that comes from. So, I ususally play a pretty tall and slow, creating a tech advantage while using habitats to get the most out of my spaceborne resources and having ecumenopolis production powerhouses.

How to play stellaris military wise