Literally typed this up
The other day and am too lazy to respond type.
https://www.newschoolers.com/forum/thread/870220/Flailing-arms---layout-help give it a quick peek.
But the most common mistake among new backflippers is they lean back while coming into the jump. it creates what I call a “sling shot” and makes so hard to actually land them. You get it around every time but the landing is non existent ie you back and headslap from the momentum of the sling shot. .
Tldr
the single greatest tip for me was to ride in with lots of shin pressure into the lip, POP,then lean back and arch your back and neck, and HAVE TO BEND THE KNEES as far back as ya can while in the air.
or just huck and pray either way as long as you don’t catch a tip