Also, facial hairs don't grow in all at once like a chia pet. Usually* takes like 15 years after puberty until someone can grow a FULL beard. So if you're drawing somebody in their teens or twenties, their beard will be patchy.
(* the order of progression is basically the same across humanity (I'm pretty sure, anyway), but different ethnicities go through the steps at different speeds. Middle-Eastern & Subcontinental folks will have full beards MUCH faster than Asian folks, for instance. (like, 20-25 years faster!))
1) Chin and moustache come in first.
- Moustache growth begins at the corners of your mouth and progresses inward toward your philtrum, but it won't actually cover your philtrum until much later.
- Chin growth begins at the very bottom of your chin in the centre, then spreads out to the sides without going past the front of your chin (i.e. not wider than your mouth), then goes up in a triangular shape toward the soul patch (but it won't grow into a soul patch right away - those hairs are VERY slow to grow), then the sides go out a bit more and then they start going up too. The progression of shapes is like an underscore shifting into a squashed acorn into an anchor and then eventually into kind of like the rebel alliance logo, and then the rest of the infill happens later, if at all (The rebel alliance shape is all UNDER your mouth. Those two side prongs will eventually reach all the way up around your mouth to connect to your moustache, but not until MUCH later)
2) While that's going on, the next zone to come in is your jawline:
- begins at corner of your jaw, then progresses down your jawline towards your chin but it WILL NOT connect to the chin's hair growth at this stage.
- when it's like halfway down your jaw it'll also begin going up to your sideburns
3) From your jawline it spreads under your jaw in to your neck (your moustache would cover your philtrum at this point, and your goatee would be at the beginnings of the rebel alliance shape)
4) then slowly begins progressing up your cheeks, following the growth pattern of your jawline hairs. But it will just be a thickening swoosh shape and not going very far up your cheeks yet. There are still NO hairs in the NO HAIR ZONE between your jawline and your goatee.
5) the goatee's rebel alliance shape has filled in and connected to your moustache, hair *starts* growing higher up your cheeks, and the NO HAIR ZONE *starts* shrinking
6) yadda yadda yadda: Full Beard!
7) you can do whatever grooming you want at any stage during this process, but you can only shave off hair from places where it's grown in the first place, and hair that has been growing for less time can't be longer than hair that's been growing for more time. So usually you'll be trimming back the earliest growth areas while you wait for the rest to catch up. ('cause if you don't it looks Fucking Terrible)
ALSO! This is the hormonal progression, not the hair-itself progression. If you're past a certain growth stage and clean-shaven, when you stop shaving your hair will start growing from everywhere on your face where facial hair has been unlocked. So once you're older than, like, 30, then you will start growing facial hair from everywhere at once like a chia pet - "5 o' clock shadow" and all that. This patchiness I've described is for *young* people (except for when it isn't because ethnicity)
(But even when you're mature, different areas of your face still have different hair-growth speeds, so it's not COMPLETELY uniform (but it's pretty close))
All of this means that if you have two people of the same ethnicity and with beards the same length, but one dude is 15 years older than the other, the older guy's beard will (usually) be thicker and more voluminous. With a long beard, the younger you are the stringier it'll be. It takes time for the slow-growth hairs to catch up to the fast ones. (But if it's LONG long, then it will tend towards being kinda thin and stringy anyway due to the attrition of shed hairs)
And if someone has a truly unkempt beard, it will be thick close to their face and will thin right out the further away from their face it gets. You'll see these in distinct bands, like a tree regrowing from being pollarded. The thickness stops shortly after their last trim, and there'll be the thin wispy band of faster-growing hairs which have overtaken the slower hairs that are bulking out the rest of the beard.
Also, the shape of a long beard will undergo plastic deformation under prolonged pressure. Sleeping on it, wearing a face mask; things of that nature. Your beard can become very misshapen until you actively restore its former lovely shape with vigorous combing and/or water:
first you comb it up and out (but mostly up) to get the maximum volume possible, and from there you gently comb it back down again into neatness. If it's undergone deformation, you can't go directly from Squarshed to Tidy, you have to 'reset' via Floof first. Or you just take a shower. (You don't have to shampoo a beard unless it's actually dirty, but you can if you want to. (but if you strip too much oil from the hair and don't put it back afterwards with conditioner or beard oil or w/ever, then your hair pulls oil from your skin and you can end up with Beard Dandruff 🙃)).
BUT if your beard just regular messy and hasn't undergone plastic deformation, like you've been hit by a strong gust of wind or whatever, then you can go quickly and directly from Mussed to Tidy. No Reset-Via-Floof required.
You can get knots in your beard, but it's highly unlikely unless your beard is LONG long. Slightly less uncommon are individual hairs getting a knot in them. As in, one individual hair will have been tied into an overhand knot, usually close to its end. You only notice these when stroking your beard and your finger happens to brush past that tiny bump in the hair; it doesn't cause any problems or anything because it's literally only affecting one single hair, not causing multiple hairs to be all stuck together. I just pull on the knot with my fingernails and the hair snaps off where the knot is.
If you braid a beard you lose most of its volume and a good bit of length. Though I guess this depends on how tight your braids are and how many of them you have... 🤔
You can disguise a really long beard as a short one by tying it up with a Gibson Tuck/inverted bun.
I think that's all the nuanced beard information I can think of right now. Happy to take questions. :)