Put weapons away after an attack, so they don’t degrade the only moon you will need your survivors constantly armed is the Nyx night attack one since you only get 2hrs before the attacks starts instead of the usual 12 you get with the other moons which provides more than enough time for your people to go get their guns.
Putting a bunch of hay floors out in small squares of about 4 tiles here and there around your base helps prevent the bugs from spawning right next to your walls, it forces them to spawn further out, have used this on insane without issue, can also help prevent the bugs spawn inside your walls if you have walled off a large amount of land that you have not gotten around to using yet. If you notice them spawning in an annoying location make a note of the location and place a bunch of floors there after the attack is dealt with, they won’t use that spot again.
Don’t go overboard though, since if they spawn further out it takes the slower ones longer to get to your base dragging out the attack longer, the timer for the next attack to occur starts the moment the attack begins not after you kill them all, on insane you can be facing an attack every 36 hrs or less once your base gets developed enough, if your unlucky you can be hit by another attack not long after the last.
The cloth sleeping bag can make a good substitute for a bed, its great since it does not block your people, you get a bunch of extra survivors later down the track and don’t have space for a bedroom, put one down in your crafting area, one in your store room etc.. provided its the only one in that room, it magically becomes a spacious bedroom, that you didn’t need to build separately, just make sure there is minimal foot traffic to prevent the disturbed sleep penalty.
You can also use them in your bunkers without them getting in the way and manually tell people to sleep in them while they wait for an attack your expecting to start in the middle of the night.
Having the right clothing can basically eliminate the need for heating and cooling devices, if you have good quality winter clothing you don’t have to worry about fires, heaters, air cons at all.
Don’t worry about stairs to turrets so long as their is another floor nearby that is next to the turret your people will be able to reach stuff that is 3 tiles higher up. Use cheap soil/hay floors for that purpose save your concrete/alloy/carbon for the floors your putting the turrets on.
Don’t be afraid to go cheap with the central floors of your buildings, you can use hay for those and only use the stronger stuff for the outer exposed sections, no point in using good strong materials on parts of a building that provided you have set your defences up well will never get attacked.
Two rows of Flamethrowers waiting on the other side of a gateway or other entrance can handle ground attacks without issue, anywhere between 4 to 9 on either side works well.
Thought the 9 on either side is for dealing with the sheer number of enemies in the hoards later into the game on insane difficulty, which can reach a point where the flamethrowers in the front will use up their entire fuel supply, that is why I add more than I would on medium, it also helps prevent the larger number of Juno from getting past the flamethrowers.
Keep the entrance to your base simple some like mazes but keeping the path finding simpler into your base can help a lot to prevent the AI attacking your bases walls rather than heading to the killzone.
Incendiary mines don’t need refuelling, you only have the initial fuel cost when making them and if they malfunction its a 5 alloy repair cost, use bear traps for your flamethrower kill area and the mines for the approach to your base since the mines will damage and stun the enemy not cause them to become trapped which I have found causes traffic jams on the way to your kill zone if you were to only use the bear traps, increasing the likelihood that bugs will try to attack your walls.
Turrets you will want to save for flyers early on until your power grid can easily sustain having them help out against ground attacks, hook them up to control switches in your defensive position where you have your survivors gather for attacks turn them on only when the flyer attack begins.
Sweet Syrup is a great staple food, keeps forever under a roof, no cooking required, mid game provided you have enough metal and power to spare, set up a few hydroponics farms and you will get a new harvest every 8 days without having to replant, though the plants will eventually start to die, and you will manually have to mark them for cutting.
I usually go with a few 10 by 5 buildings with 28 hydroponics plots, and an air con I hook up to a power switch to turn on during extreme weather so that the crops keep growing without issue. Once you have a few of those set up you can ignore cooking and pickling provided you don’t care about the happiness boost from having multiple food sources you can make it your only food source.
Once you get combat mechs you can basically ignore the tower defence side of things if you feel like it, hit the bugs once they spawn with the missile barrages then mop them up with the machine gun, you can basically scrap all your other defences at that point even on insane, which in turn will reduce the swarm sizes. That said it is not viable on the Nyx moon the one that causes night attacks since you only get 2 hours warning before the attacks starts instead of the 12 hours you get on the other difficulties.