Heya,
I'm a weirdo and shoot my 5D laying on the ground all the time. I'm one of those people that when a photo op comes up, I'm one of the first people hitting the ground. I try to remove "the ground" as a "background" that you most commonly see in photographs day to day due to the angle of view from shooting higher to lower, etc. So I'm accustomed to having dirty pants, rough elbows, and shooting weird angles with my head nearly on the ground. And I do not have Live View.
I find that when I shoot, I don't just look where my focus point is, I just know where my focus point should be and put it in the general vicinity and let depth of field take care of the rest (even when I'm shooting at F1.4). Also, I'm very often using manual focus, not autofocus, as I am much faster and better able to compose freely and focus as I wish with a manual lens and not feel compeled to put a focus point on my subject and focus/recompose, or move the focus point which takes time. I'm just faster manually. I really like the flexibility I get from that. When I do however use AF on my 5D, I'm generally just putting my focus point where my subject mostly is and again letting DOF doing the work while I compose with my peripheral vision. I'm working on 13MP, so I have less cropping room, so I try to get my angles very close to right and I do it pretty well just using peripheral vision instead of only locking my eye on the focus point on the subject and only seeing just that. I scan the whole frame, I more often don't even look right at the subject, as I know they'll be in focus most likely, so I can just see a look or moment I want to attempt to capture and just squeeze off a shot, I don't plan on being able to react to a specific smile, and then capture it--never works for candid. But preemptively taking a shot when I think a look or something is about to happen works. I try to practice predictive shooting when it comes to people; and specifically, I practice all the time on my 2 year old daughter and her 5 year old cousin.
For my wildlife shooting, I also try to get low to the ground all the time. Low perspective helps with better subject isolation. It's also a less obvious perspective because most people see things from top down perspective due to standing. I try to get down on the same eye level as the subject, or for some things like smaller species, below their eye level if possible. I use a right angle adapter on my view finder for this (I use a SeaGull Right Angle Viewfinder adapter, $50 on Amazon). This thing works fine for portrait too though. It is a right angle and can turn so you can vertical or horizontal and put the camera as low as you want to the ground, without having to literally lay down. $50 well spent for the hassle!
(LINK) Seagull right angle view finder adapter.
- With this thing, I'm only on my knees, and not on my elbows and ear to the ground anymore!
Ex of low perspective where I hit the deck (either take a knee or I literally lay down) when I know an op is about to happen:

IMAGE LINK: https://flic.kr/p/BfytrL
IMG_6096
by
Martin Wise
, on Flickr
IMAGE LINK: https://flic.kr/p/wRUDZE
IMG_4720
by
Martin Wise
, on Flickr
IMAGE LINK: https://flic.kr/p/xEhSzF
IMG_4852
by
Martin Wise
, on Flickr
IMAGE LINK: https://flic.kr/p/vCRe5X
IMG_4388
by
Martin Wise
, on Flickr
I'll even run out into the water, drop to my knees in the water, and get a low perspective:
IMAGE LINK: https://flic.kr/p/s4FDLT
IMG_3648
by
Martin Wise
, on Flickr
***************
Or, literally on my elbows in the sand at the beach:
IMAGE LINK: https://flic.kr/p/CC3EsD
a595
by
Martin Wise
, on Flickr
IMAGE LINK: https://flic.kr/p/BEwRn3
a596
by
Martin Wise
, on Flickr
Very best,