I definitely start with a circle! 
personally it depends on the pose. I always start with the head and torso (sometimes working from a line of action) but arms and hands swap depending on where i'm trying to put them. from there tho it's legs, feet and facial expressions and sometimes checking balance or flow
Griz and Norm2 i'd say have been my biggest point of reference with regards to my approach to gesture drawing among other things and then a bunch more from Thundercluck2, especially with regards to anatomy, body types and putting shapes to use
I'd say more than anything that when i'm doing gestures i kinda make anatomy a last part of focus coz more than anything i wanna make sure i'm giving a pose the feeling i want it to convey but once i feel like it's got the vibe i want then i break into stuff like making sure limbs aren't posed too unnaturally and look decent
edit: also the main reason hands can be funky for me is coz i use griz n norm's floating hands method seen here
5
it gets a lil funky but if i can find out how the arm would connect to the hand (which usually takes a lot of screwing around) then i can sort out everything else
That´s funny because the floating hands is exactly what I was thinking about this morning.
I´m working on work sheets for a comic workshop that I´m doing for kids and I love the floating
hands
Floating hands has been a lifesaver and just general tips from Griz n Norm. If anything I'd say their "animation" approach to the way they teach drawing has helped me a lot (alongside getting a grasp of posing and action from drawing Sonic for years) but finding little shortcuts or workarounds like that def help the process
I usually start with quick line of action gestures to figure out the poses, then I draw over that with sketches that will actually become the final drawing, which usually starts with the head.
I tend to start from the torso, because for me, that tends to define where the centre of gravity is and a lot of the tension or relaxation of a pose, but I do it all very loosely at first, especially if I know there will be a bunch of characters in an illo or scene, because I want to keep everyone in proportion and make sure their poses actually work together as a composition.
Generally though, I focus most on the bodyparts that define the "energy" of the pose first, and I just kinda... draw it? I don't have a rigid method now. I used to draw with more defined volumes, but I think it's one of those things you need to do less and less over time as with practice, your understanding of the volumes of the body becomes more instinctive.
I start with the head, then torso, then it depends on the pose, honestly. If legs are fully visible they will probably go first since they are a more natural continuation from the torso through hips.
That´s exactly how I do it too. I start with the torso for the same reason.
Either line of action and torso or I start with the torso for simple figures.
I used to draw the head first as a kid but it never looked right and I have the feeling
of being in way better control over the proportions and balance of the figure since
I started with the torso and now the head is usually the last thing that I draw and
I feel like it´s easy when everything else looks good
99% of time it's the head with rough "central" mark where the middle of the face and eyes should be and an ear, but I may change their position in process. I guess I can say I get lost if I start from any other body part, because I see head as a "crown center" and drawing a headless figure is honestly a pain. I can imagine I would probably sketch a head even for a headless character 
And then just going going down: shoulders/torso, if it's a full body I'll probably sketch legs first, arms after that, but it depends.
I never really got the idea of how the line of action or the center of gravity works, like, I get the idea on paper, but can't implement it 
Instead it makes much more sense to just sketch the general what goes where.
I do what stands out first which is usually the head.
Or sometimes just a blob which I guess is more like the line of action.
I like blobs because I want to see the volume too.
Yes, that´s what I will be trying to teach the kids too, getting some volume on the page.
It´s just better than just trying to start with the outlines and getting lost
I draw a round shape for the head first
it's not really a circle because I honestly don't give a crap refining it and I just work with whatever shape I throw at the wall
I think it is different everytime for me.
I usually start with head but there are times when the torso is my beginning charm.
Well, it depends on the posture a lot.
For bending poses, you would want to start with the waist and buttocks.
For poses where the pov is from below, you might want to draw a light sketch starting from feet to give you a proper picture.
For a lot of poses where body language matters, you might wanna begin with a rough body sketch consisting just circles and triangles and then begin the actual picture.
Gestures and sign poses usually begin with hands.
But suprisingly for a few people, the head is always the beginning no matter what pose.
A fair number of newbies and experts are comfortable with a quick line of action and then start with the main focus of the pose.
I personally advice (from experience) to just figure out whatever you are comfortable with rather than what is ideal. Since a lot of people just drift off from a fantastic style of artwork just to fit in the ideal way of drawing.
I 100% agree with the last thing you wrote to finger out whatever you are comfortable with.
I never was comfortable with drawing the head first and many instructors showed it like that
and it´s really frustrating to try when it doesn´t work for you and I´m super happy now with my
technique. I also have some poses and figures where I first draw a shape which represents where
the sternum will go. It works really well for and might not work for other people
Blob gang 
Basically for me I block out the location of the character with a shape that looks like one of those murder scene outlines 
(I like blobs because they help me visualize the composition of the image better; with a line of action, I feel like I have no idea where the character actually is XD
If I'm tracing a pose directly from a reference, then head. Without a reference, then I'm definitely going for a line of action first. For just a bust shot, I'll just star with the head.
It's great because in like 5 seconds you can see if the size and placement is wrong
Which happens to me a lot!
For me it depends what the focus of the panel is supposed to be. If it's to show emotion or a reaction I'll draw the face first and spend more time making sure that's correct. The rest doesn't really matter right?
If a panel has a full body in it and the focus of the panel is on showing an action of some sort (jumping, falling, catching etc) I try to capture the energy I want with a quick sketch. Just shapes really. I try to preserve that initial sketch all the way through to the end and change very little. If I overwork a body it tends to become stiff. Faster sketches = more energy, at least for me.
In terms of how I literally sketch a full body I suppose I start with a circle head and then the shoulder line, arm lines, and back line? It depends how the person is standing. I draw where the weight is first I guess? It's hard to say.