I hope to keep this tutorial relatively short and simple. The ship I've used uses a simplified hull (although I'll explain how to make it better using decorations). I'm mostly going to just show it through images as for me there isn't much to say. I won't talk about proper armoring or turret layout or even the interior layout of the ship as that stuff always changes based off the ship you're building and the materials you use.
To sum up everything I've just said, this is a simple tutorial that will only really touch on aesthetics without compromising performance in a significant way.I've tried to use as simple words as possible to make this guide accessible to everyone.

The first step of building a hull for me is outlining. All I really do is plan around the length and width of the ship and try to make a smooth design that fits with the type of ship I'm trying to make. A general tip would be that the further back you get from the widest point, the more the hull will curve inwards. I usually leave the bottom of the ship flat until the front, but the rear should be designed later for the most part after you know what you're doing.
I usually add turrets for sizing to make sure there is enough space in the finished model.
For a slope on the front of the ship. I usually plan out using spin blocks sloping to a point I've set with slopes at the end. This is the most tedious and annoying part of hull building for me, and it often presents a large weakness in actual ship designs as a large chunk of the deck just gets blown off by one shot.
]Over the course of the last two images I slowly built up the hull, trying to keep it as smooth as possible. Usually using 4m offsets and slopes is the best strategy. (If you are going to cover it in mimics, you can also use applique slopes) If you really want the smoothest looking hull, I'd recommend using decorations to expand the slopes to go all the way up to the next slope. (For a good example, look at my Tappan class) Keep in mind that mimics and decorations can be moved by incredibly small amounts by tying in the distance you want manually as to prevent annoying overlapping objects with different textures or colors.
[previewimg=21645745;sizeFull,floatLeft;2020-12-17_16 12 00.png][/previewimg] Above is another view of the hull from the side. The bottom of the hull is often somewhat distorted by the bulge on the front of a ship. (I definitely have other ships that are good examples of this, but this is probably not good for the forward water drag of the hull) [previewimg=21645748;sizeFull,floatLeft;2020-12-17_16 28 50.png][/previewimg] At this stage I armor up the weapon systems on the ship. [previewimg=21645751;sizeFull,floatLeft;2020-12-17_16 40 01.png][/previewimg] I then design the rear segment around those weapons. This part is hard to explain as it is different for all ships based off there weaponry, so I'd suggest looking for examples for this section or just sticking with a simple fixed slope till you feel comfortable designing this part. [previewimg=21645754;sizeFull,floatLeft;2020-12-17_16 49 17.png][/previewimg] I usually put in the ammo storage after this. [previewimg=21645763;sizeFull,floatLeft;2020-12-17_19 13 00.jpg][/previewimg] A pretty big jump, but I've continued adding in internal systems and chose to put in some huge missiles because I had the extra space. [previewimg=21645767;sizeFull,floatLeft;2020-12-18_11 36 51.jpg][/previewimg] As this is a faction ship, I've buiAfter this, I usually go in a fill in the bottom of the hull. I use the offset slopes that transition between two sizes to make the bottom smooth. (Although I think most of my ships uses this, I think the mountain class is a good example for cruiser hull design that isn't to complex).
Above is another view of the hull from the side. The bottom of the hull is often somewhat distorted by the bulge on the front of a ship. (I definitely have other ships that are good examples of this, but this is probably not good for the forward water drag of the hull)
At this stage I armor up the weapon systems on the ship.
I then design the rear segment around those weapons. This part is hard to explain as it is different for all ships based off there weaponry, so I'd suggest looking for examples for this section or just sticking with a simple fixed slope till you feel comfortable designing this part.
I usually put in the ammo storage after this.
A pretty big jump, but I've continued adding in internal systems and chose to put in some huge missiles because I had the extra space.
As this is a faction ship, I've built in some weaknesses such as the oddly placed engine, but I'd always recommend putting the engine in somewhere safe where it can vent underwater.

There is an error in the middle of this section but I can't seem to fix it. Ignore the section where it has the random images not showing.

After all that, the ship is ready for weapons testing and systems testing. I also inserted my secondary turrets/CIWS in slots I made while I was designing the hull. For my secondary turrets, I usually just create a 3x3 hole that I can insert them into.
After this, I line up the turrets so they can all turn to fire and then build up the deck beneath them.I build the superstructure from front to back to try to get things to line up better.
After this I armored up the missiles to make sure I'd have room for the rest of the superstructure without messing up the weapons.
I then put in two smoke stacks behind the main superstructure.
For better examples of cruisers, look at the superstructures on the Kalinin and Mountain.
Following all this, I plop down some decorations that I have saved on my test platform. Unfortunately there isn't much I can recommend for designing decorations. That is just something that requires practice. I've spent a lot of time working on mimic designs and I'm not even too good at them.
The finished ship above.
Although not really optimized or anything. This ship may use simplified version of stuff I normally do, but this just goes to show how much you can do without compromising to much performance.

The biggest tip I can give at the end of this is just look at what other people have done and how ships look in real life. I recommend just playing around with decorations to see how things blend and work together.

If you have any questions, feel free to message me.
I've been told on numerous occasions that I'm pretty bad at explaining stuff, but I hope this guide has been helpful to everyone.