I come from a school of thought that crashing is instructive. If you aren't pushing skills to the edge and occasionally over then perhaps you need to step it up some and push a little harder. Conversely, if you are crashing hard every time you get out on the trails then you should perhaps dial it back a couple of notches.
Oh yeah, this crashing is good mentality doesn't really apply on the road. Crashing on the road generally means very bad things. And usually a road crash isn't even the cyclist's fault, its usually some impatient cager who passes dangerously and clips the cyclist or an asleep behind the wheel sheriff's deputy or someone making an illegal turn in front of you.
Can you guess that I'm not much of a fan of road riding? Too many factors are out of my hands on the road, too many hurtling loonies rushing around without regard for others, too many I've-had-a-bad-day assholes. Nope, I'm a trail rider.
I used to think that trees were better because they don't jump out into your path only I had one jump out into my path yesterday and side swipe me on my way by (yeah, I know it was really rider error but it makes me feel a tiny bit better to blame it on the tree). And I'd expected the scrapes to have purpled up by this morning but nope, they look like a bear scratches on my side, not too bad but kind of annoying.
Anyway, back to the post at hand. You can learn from crashing, you can learn what you need to work on, you can learn that your bike's brakes need adjustment, you can learn that pricker bushes are no fun to crash into, you can learn how to more gracefully go over your handlebars and tumble without causing massive harm.
Of course, it should go without saying, before you go out and push your envelope, gear up. Get a good helmet (maybe even one of those full face motorcross looking ones), gloves, maybe some arm guards and leg guards if you're really going to go wild. Riding off road without protective gear is really, really stupid. But then, I'm now old enough to have learned just how breakable the human body is. I don't go full on crash gear, usually sticking with a good helmet and gloves but that's mostly because I'm not a jumper, I'm a cross country rider who occasionally gets off the ground. I'm learning how to safely jump some but its a slow learning curve for me.
Have fun and push yourself a little further and a little harder each time and you'll find your skills and your enjoyment of mountain biking increasing too.
** Photo credit is from Injury.com **