Death is a hard subject to talk about for many people. It frightens many people. The fear is not of death, but rather comes from not knowing what will happen to us when we die (even if we have our own ideas about the subject). It is a fear of change, a fear of the unknown. It is a natural fear, but it is not a fear of death itself. Death is a part of the life cycle. Without death we would die out because we would over populate ourselves so quickly.
Some people feel that we die when we learn what we came here to learn. Or that we die when God says it is time. Or that we die when our bodies have grown too weak to keep us around. Whatever you feel it is always unexpected death that is the hardest to deal with. When someone we love dies do we respond with gladness that it was time for them to move on and celebrate their life? Or do we mourn their passing as though death was a horrible thing? Which would you prefer people do for you?
It hurts when a person we love dies, because we will never see them in the flesh again, but if we believe they will still be there watching over us at least for a time it helps. Think about your reaction to death. Are you sad that they will miss certain events in your life, like a wedding or the birth of a child? More importantly are you sad for them or for you because they won't be there for you? It's the difference between "I'm sad my father won't be at my wedding I know he would have wanted to be," and "I'm sad my father won't be at my wedding because I wanted him to be there." If it will comfort you then believe they will be there in spirit. I personally feel that way and know that my father was at my wedding in spirit.
It is very easy to resent a person for leaving us through death. It is also unhealthy and stressful in the long run. It is something you should work on as soon as you can if you find your self feeling that way.
The concept of death is very hard for children to understand. In today's society where TV shows characters dying and then coming back on the next show and where video games give you more lives the more coins you feed them it is hard to explain the permanence of death to a child. It is hard for them to understand why they don't come back. If you can start explaining the life cycle at an early age it should be easier. If children understand that they have a spirit and it is their spirit that lives in their dreams it will be easier to understand why grandmother's body is in the casket, but she's not really there. If you can explain that the spirit part of her felt it was time to go on to (Heaven, Nirvana, her next incarnation, join the spirit world, etc...) it will be an understandable and not a scary event. Explaining that just dreaming is much different and you can visit grandmother in your dreams, but that you won't be able to join her where she has gone till it is your time will help. Be honest that you don't know what the child's time to pass on is and that you don't know what your time to pass on is, but reassure them that you are sure it won't be for a long time.
Children will look to you as to how to deal with death. If you yourself can't deal with it then they won't be able to either and will cause you to be even more stressed out then you would be anyway. Make sure you come to terms with a passing in your family as quickly as you can so that you can help your children understand and not fear death.
Here is a simple visualization that can help describe death to a child
Picture a balloon, full of air, able to bounce around, big and bold and beautiful.
When its time is over, it goes down, either with a bang all at once (like an accident) or very slowly over time (like an illness.) Finally, all the air is gone. The balloon is different; it is flat and lifeless. The breeze doesn't bounce it about any more because the air has gone.
But what has happened to the air? No longer stuck inside the balloon, it has spread and caught a breeze and moved on, free at last.
Earth brings us into life
Do not stand at my grave and weep
There is information on death rituals in the Life rituals and Ceremonies Section.