Once again, every sport can be dangerous, even chess. I know guys
who get tennis elbow from moving the pieces...and static butt, of
course.
Tack some lightweight EVA foam padding to your butt and knees.
As in football or karate, you roll with the fall, not stick a stupid
arm out to resist it.
Keep your knees bent at all times, while riding.
Beginning is always the most dangerous time, I hope you get over it.
For me, the worst first day was my stomach muscles getting sore, as
did my shoulder deltoids from getting up so many times.
After that first 2 hour day, I could link turns, carve a bit, and
float thru powder without catching rails ever again.
As far as Tucks, I can say I skied Chute75 at Squaw my 10th day ever,
and I'd suspect could have snowboarded it just barely sooner.
But it isn't about how fast you progress, unless your 19 and strong.
Most of my friends actually learned faster, as they didn't have the
disadvantage of being an advanced skier.