If you get into a situation where you are falling from your motorcycle, it can happen so quickly there isn't a lot of time to stop and remember proper techniques for falling or what you should and shouldn't do with your body position and you may have no ability to control yourself even if you can think of what to do in any event.
However, knowing how to fall is one of the keys to not being injured in the event of a spill on your dirt bike or motorcycle. First, let's talk about a low side fall. This is when you fall off and your bike winds up out in front of you. In the event of a fall, always try to stay behind your bike, push off if you need to. If you can, try to roll onto your back and spread yourself out to make the most surface contact possible which will slow you down. Do not attempt to get up in anyway until you're completely sure you have come to a full stop. Flailing your arms and legs during a fall can break bones.
The other end of the falling spectrum is a type of fall called a high side. In this case you have the unwelcome position of being in front of your motorcycle after the spill. You really want to make sure you don't come to a stop until after your motorcycle does. In this case, your best bet is to tuck your arms and legs in to lessen your amount of surface friction to keep moving longer and with any luck, away from your bike.
There is no sure fire way to control yourself during a fall, but use these tips to lessen the severity of a situation if you happen to have a spill while riding your dirt bike.