Teach kids not to put their hands or feet anywhere they can’t see first—tall grass, rocks, woodpiles.
If there is a snake bite, stay calm. Don’t cut the wound open or try to suck anything out. Don’t use a tourniquet.
Keep the bite lower than the heart, avoid moving the area as best as possible, and get medical care.
Here’s one good guide to snakebite first aid.
Read more about rattlesnakes from the California Department of Fish and Wildlife here.