Know your group. Carry a cell phone. Carry a good map and know where you are. Carry first aid supplies. If there are sufficient hikers do not leave the injured person alone and when sending for aid send three or four, these hikers should carry a cell phone, map and whistle.
All hikers are to be encouraged to carry a whistle and know the code - see below.
It is your responsibility to look at your own medical history and problems that you may develop and carry those special supplies you need. Items that are consumed frequently such as Band-Aids, moleskin and aspirin or Tylenol are best kept in a separate small kit so they can be accessed without disturbing your main kit. Finally, don't forget to check your kit periodically and replace any items that have been consumed or have deteriorated.