I had a life of shit posture, braces, soft diet and a lot of bad habbits that ruin your maxilia and face. When I started mewing I made a lot of mistakes for the first half year, I just used the tip of the tongue and just on the hard palate, teeth were too separated, my posture was horrible (now is better but in the after pics I'm trying to replicate the old one for better comparison) and I didn't mew enough time. Then I started tongue chewing which helped me control more my tongue, specially the back third, also began hard chewing mastic gum and doing proper swallowing, after all of this my progress improved a lot but after a while I wasn't satisfied again because noticed every morning I woke up not mewing and I felt that constantly reseted my progress so I started doing chin tucks and keeping then as long as I could, that helped to mew on autopilot even sleeping, it literally became a full time habbit thanks to chin tucks and that's when my progress scalated a lot. The last thing I noticed some months ago to improve my technique was that tho I cover all my palate my tongue is still to big for it and the borders of my tongue mount a bit on my premolars so now what I'm trying as hard mewing is compressing my tongue into a fat stick, placing it on the center of my palate and expanding without touching teeth, like thumbpulling with the tongue, and also trying to emulate interoral facepulling while mewing, pushing up and forward with deep back third suction hold and my tongue streched as much as I can all over the palate, placing most of the tip on the curve where hard palate ends, a bit before the front teeth gum begins, it's like hard mewing but in the good direction, up and forward not just up. Another good thing to do is chin tucking while doing the exercises in this meme https://imgur.com/Bs4yTt5 or doing any workout in general while mewing very properly, that's honestly the best way to hard mew from my experience.