I recommend folk check out these articles for shooting prone:
Now i'm not sure about the absolute "correctness" of that blog but I did try some of the ideas and found some good tips. Enough help that I trust the blog enough to try more ideas from it.
Take Rifleman1176's post:
Good luck. I have never been able to shoot prone. I can't breath when laying down like that, even when I was young and slender. My elbows roll around like they are ball bearings.
I had the same issues as Rifleman but these articles had some tips that completely resolved my breathing and elbow issues.
Over 200 articles relating to rifle shooting (look under "blog archives" in the lower right hand side). I'm sure it's not perfect and some will post every little "perceived" error but it's a lot better than just rollin around in the dirt with zero idea what we are doing.