I crashed the first time I rode my bike. As a researcher, I looked into the best way to heal. Barring any internal injuries or significant skin rashes, the most critical parts for recovery are the joints. They can never be the same if they're not taken care of properly. Everyone in sports already knows about RICE, as another poster mentioned here. However, a more recent research shows that RICE can be detrimental to recovery. There is a better road to recovery: MEAT - Movement, Exercise, Analgesia, Treatment. Many doctors don't even know about this since most don't keep up with recent research. Since I don't want to write a long essay on this, here is the general idea:

The first 24-48 hours you want to use RICE to allow for some healing
After that, you must start MEAT. Movement must be gentle, like drawing the alphabet in the air
Exercise should be light - stop if the pain becomes acute to prevent further damage.
Analgesia involves only pain killers (if you have to). The idea is that if you take
something to prevent swelling, you will hinder the healing process.
Treatment involves both cold and hot compresses. Do 10 minutes of cold followed by 50 minutes of hot. What this does is increase blood flow to the damaged area and wash away scar tissue.

It is also important to get an X-ray if any of your joints hurt a lot. Broken or fractures bones must be healed differently.