If you lose your light, you can lose your life. Always wear a helmet. It's not even falling rocks you need to worry about so much as smacking your head. You get a concussion, you go into shock, hypothermia, and then die. Always bring the right equipment.
Good lug soled boots can ensure safe footing.
Long pants and a warm shirt are a must in potentially cold caves. Gloves will save your hands. Your vertical equipment should be of good quality and well maintained. Never cave alone. If you cave alone, you die alone.