I try to fall on my side mainly, on the hip & thigh, while lifting my head up so it does not hit the ground. In certain situations like going over the front of the bike/handlebars & you can not clear the bike or bikes, then I will stick my arms out to avoid a head injury/concussion. Had a concussion as a kid which is worst thing that ever happened to me.
Sorry about your concussion above. Take it your helmet was destroyed.