Well ... it depends.
First of all, Cannon-Cannon is always an excellent fallback for destruction. It's an excellent weapon for DPM, and it can shoot down missiles on its way to the target. If it's a small setup (total size in the hundreds of blocks), Overdrive is an excellent way to boost FIREPOWER at the expense of POWER. It is more space-efficient than simply adding more cannon modules (cannot go past 100% effect though) but it takes 6x more power than they do.
For large cannons (thousands of modules if it's Cannon-Cannon, because the Cannon secondary reduces damage) explosive effect is a good way to spread damage to surrounding blocks. Just watch out - when you build this giant cannon, it CAN overpenetrate targets and go right on through, not expending all its damage.
Missiles are good. Missile-Missile combo is heatseeking - no good if there's anything friendly in the area besides the shooting vessel/turret. Missile-Pulse-Explosive is generally called a nuke. At 100% Pulse effect, it can take a full minute to reload, but at lower percentages it takes less time - dealing less damage. Explosive effect tertiary increases the radius of damage caused, and is a must for large missiles to cause real damage. Also, Missile-Beam is a very longranged weapon and it tracks, moving quickly too - an excellent weapon. Loads far faster than a nuke but slightly slower than straight missiles. I think. Missile-cannon is only useful if you're on a ship and you get up close and personal. Then ... well, Idk, but it seems effective. Missile-Beam and Missile-Pulse track, so they require little effort on the part of the shooter. Point, wait for the reticle to start flashing, and click. Also, AIs don't have to wait for a "Lock" - they get it instantly.
Beams have the longest range. Beam-Beam engages far out of the ranges of other weapons, so is an excellent sniper weapon, though it lacks in hull damage. Beams have excellent shield damage, however. I haven't tried them too much, however, because cannons seem to be better all-round weapons on the small vessels I've built so far. But you know, try and find out. Build a block - literally. Armor chunk in front, some random system blocks in the back. Very, very thick on both. Test your weapons on it.
So ... every noob should know that on a station, you place shields. Ridiculous, absurd, stupid amounts of shields. My probably mid-sized (the size of a pirate station, different shape and denser in systems blocks) has 10.5 mil shields and 1.45 mil regen. If you're building small, you won't fit more than a few million shield cap and half a mil regen if you go ridiculous on it. This is because they cannot run away, cannot be repaired via blueprint or shipyard, and cannot maneuver to dodge fire.
Second, you need AMS turrets. Cannon-Cannon setups. One module each is a usual. Just pours fire out.
Third, it must have a factory and refinery setup. And cargo storage. It's absolutely necessary - because you have the room, you're expected to use it. And there's no point not having that stuff on a base.
A small shipyard is also a good idea for a smaller station. Or a big one, whatever. This lets you build ships easily on-site. And repair them easily. And ... well ... glitch them into holograms long after you've built them, delete them entirely from systems away, fling turrets int- let's not get into all that. Mind the glitches.
Fooouuurrrtthhh.... Turrets!
More turrets!
Furniture is restricted, currently, by most people, to wedges. Yep, that's it. Wedges sitting like big chairs on the ground. That's it. You can go fancier but really, do as you wish. You can only sit on wedges and cubes, keep that in mind though.
For medbays ... Functionally? A room, any room, with "Medical Cabinets" or "Medical Supplies". Decoration? Beds, curtains, operating table with lights, anything else you can imagine. Body disposal chute.
Access corridors? Usually, 3x3 blocks wide, mostly with wedges on the inside corners to give a rounded feel. It's nicer than a straight wall.
Hangars? Well, build one to suit whatever small ships you've built. Decoration can be gantries made out of scaffold or Alloyed Metal Mesh, random boxes, consoles, whatnot, storages (with practical purposes too lol), other small docked vessels, anti-intruder turrets (yeah ... highly recommended), anti-intruder mechs (See Dr. Whammy's shipyard), All-Heck's-Goin-Loose-Drop-The-Drones Button near the door ... use your imagination. Or it could just have bare racks to hold tons of TIE fighters to rain death and destruction on the good guys - I mean opponents of order, integrity, corruption, and crue- whoops, slipped again.
Use your imagination. Build whatever. We won't laugh for too long if your flamingo-shaped turret blasts a Titan out from under us. Not once it starts blazing rockets or whatnot.