My thought process for when I draw my bug people so far...
As I've mentioned a couple times before, there is a lot I take into consideration when drawing my bug people, and I'll go over everything in depth so it's clear why I do what I do when drawing them.
The body structure is something that is one of the most important things I take into account when drawing, and I'll go over some different details I use. First off, there is a small example of sexual dimorphism I use, you see it clearly in the chest. Females have a sharper and more prominent chest while males have a smoother, rounder one. This is mostly to make it more clear as to which gender a specific bug I've drawn belongs to. Every bug that has a body type that ISN'T the Centipede body type has a noticeable hourglass figure, this is intentional. One of the reasons for this is because of what bugs have that humans don't; chitin. Chitin is not very flexible, and cannot stretch like human skin. The other reason is because bugs don't have bones, so they don't have a spine, however, they still need to be able to bend. This is where the hourglass figure comes into play, because at the narrowest point there is a joint of sorts that allows the bug to tilt their torso without tilting the rest of their body. Another thing about the body structure I think about when drawing is how they are able to walk. Every bug person I have and will ever draw should be able to go down on all their legs and arms and walk like their real world counterparts comfortably. Speaking of walking, I should talk about the feet I use, because which shape or features I use is very important.
Insect feet are vaguely similar to human feet in shape, and there are a few joints in the feet that allow them to bend, but that's where the similarities end. Insect feet have three sort of talons, two long ones in the front, and a single short one in the back, and all three serve a purpose. When an insect walks, and for this example let's assume they are walking outside on the ground, the short talon touches the dirt first and sinks in, acting as a sort of anchor. Then, the foot rolls forwards and as the two front talons touch the ground, the foot lifts the short talon out and uses the front two talons to steady themselves as their other foot repeats the process. When running, however, the short talon almost never touches the ground, and instead the feet continuously push off the ground with the front talons. While this is similar to how humans sprint, it isn't as effective as you might think as those two talons keep digging into the ground which causes speed to be lost due to how long those two talons are, and that there's a talon on their heel, and the friction caused by them sinking into the ground, as they are built to firmly grip onto things, unlike human feet. Bugs are also not as good as turning as humans are, and have to make a large arc or slow down and reorient themselves to turn, unlike humans who can turn on a dime. Because of this, you can gain distance from an aggressive bug by quickly turning around corners or weaving through trees, which the bug cannot do as effectively. Also, there are very few bugs that can run faster than a human at full sprint, but there are NO bugs that have nearly as much endurance as a human, therefore, a human does not need to run faster, just longer, and can do just that quite easily. Even the Goliath Maneater Tarantula, which can sprint at about 35 mp/h (around 56 km/h) can only do so for around 10 seconds before tiring, but I digress. Speaking of Spiders, they have a very different foot shape as well. At first glance, it look almost like a padded nub with three talons sticking out in front, and up close, you'll find it's structured almost like a paw, but not nearly as malleable. They also have more than just the three easily seen talons too, they have several that remain hidden underneath the hair. This allows them to grab onto surfaces while climbing easier, and also grab onto the web strands they make. The shorter front talons cause less friction whem they run, which means they can run much faster than insects, though they tend to tire faster as well. When they walk, they lean forwards a bit and reach out their leg and place it flatly on the ground, making it look like they're tiptoeing. This makes them rather quiet when they walk. Scorpion feet are longer than Spider feet, but shorter than insect feet, and have two talons in front and one in the back like insects, yet their length, which falls generally between Spider and insect feet gives them a mix of both advantages and disadvantages. Scorpions who live in lusher environments like forests and jungles usually have longer feet as a result, and those who live in more barren environments like deserts and savannahs tend to have shorter feet. They walk and run in much the same way as insects too, though they are a bit more effective at it.
However, where they lack in running efficiency they excel in climbing. When a bug climbs, it does so with a sort of "every other" gait, meaning that they move one arm in the first applicable pair, then move the alternatating arm in the next down pair, then do the same with the next all the way down to their legs, which follow the same rule. They then pull themselves up with those limbs and repeat the process with the other limbs that were used in the previous cycle, and can do this quite quickly.
I currently have several different body types I choose from when I draw a bug, though a few look similar. While I have explained a lot of the structuring for the body types for insects and arachnids, I have yet to explain the myriapod body type, which includes Centipedes, Millipedes, and Isopods. Unlike the more anthropomorphic insects and arachnids, these bugs are closer to their real world counterparts. Sporting at least a dozen limbs, each one is an arm, and each one ends in a hand. These bugs always move as if they are climbing, and are quite fast to boot. Their almost serpentine body allows them to tense their muscles and spring forward towards escaping prey, and allow them to constrict them too. However, they usually won't need to, as they either have other methods of taking out prey, like a Centipede's venom, or have a more herbivorous diet, like Millipedes. While it may not seem like it, they DO actually have a torso of sorts, but no waist, and generally includes their first four pairs of arms.
Now, for sizes, there is a lot I reference when choosing sizes for each bug or character. The first of which is their species and how big that species is relative to any other bug species. Next, I take their sex into account, whether that species has size as a sexual dimorphic trait or not. After that, I reference their body type. Insects have the smallest body type, arachnids are a step up, and myriapods are the largest by far. Finally, I use the heights of Naomi Dectra and her husband, and compare how big visually they should be next to those two, and it's at that point I choose a specific height for the individual.
As of now, this is everything I use, but I will update this if there is a change, addition, or removal of something to this. There might be something I'm forgetting, however, and if you notice something I do you would want to understand why I do it, then mention it in a comment and I'll answer, if I have an answer, and add it to this post.