Another huge thing to consider is if the vessel needs to land on a planet.

When I'm building ships, I tend to naturally gravitate towards the highly elegant, yet entirely functional, "brick" shape inspired by legendary examples such as Fiat Ducato, Renault Master, and Volkswagen Transporter. Only very few cars manage to strike the sweet spot of graceful design as the Volvo 740 has,  and replicating the essence of those supremely exquisite straight lines has been surprisingly challenging, yet rewarding.

I mainly build using the “cock and balls” shape. This is due to me wanting to maximize reverse thrust. Also it works with my fleet tactics since I make use of forward static rail guns in my larger ships. The design allows me to maximize space for my static weapons to snipe targets with rail guns before they get into range.

an aspect I use when designing my own ships to make them stand out more is what I call "Breaking the center line"  where I will deliberately offset some structures like nacelles or the bow of a ship along the lateral axis then add super structures to keep the over all appearance of balance.  this is a purely aesthetic design feature but it can create very visually striking ships in the same way asymmetry can.

Another thing to remember is function.

A logistical frigate will look far different from a missle or screening frigate.

Form will follow function and as far a military ships go you should make your the best at what ever job its built for.

I'm a fan of the less common horse shoe shape, or "U" shape.
It's excellent for industrial roles.
Remember, there's more to SE than just PvP ship combat.

Personally, I enjoy designing industrial ships, because everyone and their grandma build combat ships, but you don't see industrial or utility ships as often, and it's nice to fill that niche in the workshop. Building novelty ships and base props is also a ton of fun, and again, such builds seem uncommon in the workshop.

4:35 got me so good, that delivery was impeccable.

Another few suggestions I would give for this:
Give your faction a main shape - For example the winged dagger shape for most of my fleet, giving most of your ships a similar shape allows for a more cohesive faction design.
Don't be afraid to try different shapes - Even if you set a main shape for your faction, feel free to try other shapes that compliment it well. A front heavy hammerhead and a back heavy winged dagger both compliment each other by being opposites.
Make your ships distinct - While ships from a faction should all look similar, you should make them identifiable by a black and white silhouette.
Try asymmetry - Even as simple as putting an antenna on one side and not on the other, or as complex as making each half of the ship look completely different, it can add uniqueness to a build.
Don't have everything smooth - Even if your faction's style is smoothed out curved ships, adding some raised bits with some sharper angles gives more visual interest to the build.

Caught me off guard when you said “cock and balls design”

I almost exclusively play single player survival without combat so my qualifications for a vessels shape are entirely different. I let the utility of the the ship determine it's final shape. I'll start with defining a ships purpose (mining, hauling, etc) and start by connecting all of the largest blocks like jump drives and hydrogen tanks together in a rough shape then move things around little by little until i can neatly fit in all the small functional blocks like batteries, gyros, and assemblers in the ship. Once it's has all the utility blocks i want i'll add the minimal amount of armor blocks necessary to protect the most vulnerable parts and perhaps a little more to make the form flow a little better.
In the end it's the large blocks that get added that will determine the ships overall size, in that way i maximize the ships utility and minimize things like redundant conveyor lines and wasted space between the outer armor and the internal components thus keeping the ship as light and cheap to build as possible.

I wouldn't worry so much about hull shape as I would system layout, especially if you're making a H2 ship.
Build your internals layout first, then figure out your hull shape. Nothing's worse than making an awesome looking ship, but then you have no internal space to add vital systems and make good looking, well thought out interiors.

I'm not really sure who still pays attention to this video's comment section still, however there is one ship design shape that most forget about: the barbell. Great for massive thrust as well as the advantages of the hammerhead and possibly mounting points for a carrier's compliment of support craft with the same minimal space drawbacks as the pure rectangular style.

For me it's all about "form follow functions", I start with 1 or 2 specific features in mind, such as a main weapon, high cargo capacity, or perhaps even huge thrusters, and build everything around that.

The design should highlight that feature, and every major shape must have a reason to exist.

I like using thin walls around functional parts, and use a lot of heavy armor to compensate for how thin the armor is, it allows for very compact but still fairly resilient ships.

One last advice, do not hesitate to use weird parts as aesthetic, for instance, conveyor tubes are an easy way to beef up the barrel of a custom turret.

I’m glad I’m not the only one who seems to naturally stuff all my maneuvering thrusters into two testicles for my ship.

Whats with vertical designs? Be it in the homeworld mothership layout or with thrust gravity in mind like in the expanse? I think i saw a few of the former designs in the workshop.

Most ppl: build complex ship forms
Me: T R I A N G L E

I've been playing this game since it came out, I built to vessels when I started, both named the Q Bound, one standard, and the other was an upgraded version both about the size of a Aircraft carrier. I now found I am building bits of vessels, I.e. rear engine sections, forward cockpit, middle sections, etc, then play around by joining them together with merg connectors.

From my 9 years playing: Build from inside out. Stop making everything smooth. Take a break from military ships. Stop making triangles. Give all armor a purpose- don't just add a nose or a pylon that protects or houses nothing.

More advanced tips:

Avoid repeating textures. Don't be scared of flat surfaces. Give yourself limitations. Echo design elements. Limit fake greeble.

I've been working on a destroyer with a Hammerhead shape in starship Evo recently. The idea being that it could use it's big head to block shots, kinda like a physical shield.

The kok n baulls shape

Also, I like the new intro, though your intro is the reason I listen to that one abba song