It's often been quoted that the main difference between us and [insert monstrous invader of your choice] is that we bury our dead. It is, for some reason, something that we identify as a key factor of being human - that we have a ritual to honour and mark the passage of our friends and kin.

Animals don't bury their dead - with the exception perhaps of elephants, few animals die in such a peaceful fashion as to allow it. Usually, nature takes care of the basic process, and the dead are someone else's lunch. If you're being hunted by lions as a matter of course, it makes little sense to risk your whole herd in order to perform a ritual for a member who's no longer there. 

It's a recognised luxury, however - whenever the dead start to outnumber those who are left to bury them, rituals tend to go out the window. Consider the mass graves during the plagues (and that was at a time when the law decreed the dead had to be dealt with for the survival of everyone else). Any horror movie or video game will show you - dead left where they lay signifies total social panic - a regression back into our animal values - survivalist rather than social. 

What your society does with its dead speaks volumes. Their mythology and religion is laid bare by the basic rituals (or lack thereof) that mark important life moments - birth, death, marriage or mating, entering adulthood.

This is another area where we're easily blinded by our own culture. It's far too easy to drop burial into a culture without considering the ramifications, or the origins of our own practices. The use of coffins, for example, or the depth of burial, the orientation of the corpse, the presence of family members - all things that are born of our own religion and mythology. It makes about as much sense to transplant these directly as it does to transplant Easter eggs.

Consider what you've already created for these people. What do they believe in, what do they believe happens after death? What parts of their body do they hold sacred (if any?). 

What kind of environment do they live in? The environment will have some impact on burial customs - it's difficult to bury someone formally in mangroves, for example - but that may be mitigated by other factors. Their original customs may have come about when they were living in a different environment, for example, or the degree of difficulty may be an extra honour to the dead. The use of the particular ritual may even be causing tension in the people, if precious resources are being 'wasted' on the dead. Rituals can reveal your people's history as well as their culture and values.

There are no set 'rules' for funeral rites. Only two components to really consider:

• The corpse must be disposed of in some way. Left behind, covered, burned, eaten, preserved, piled in a mound, spreadeagled as a sacrifice - you have do to something with the corpse - or have a very good reason that your people leave it in the living room where it died. Remember, corpses will attract vermin, predators, scavengers and disease if not dealt with - ignore at your own peril.
• Some process of grieving will be initiated. Here's where crazy wacky rituals can be fun and revealing. Funerals don't have to be sad, they don't even have to be about the person who has passed; perhaps it's a thanksgiving that a vengeful god has taken someone else and not us, or a humble recognition of our own mortality. The society should, in some way, mark the loss and make room for grief. Unless you're creating a society of psychopaths, but even they may ritualise the distribution of the deceased's estate and belongings.

Those two components should feed into one another, however. Either by contradicting or by reinforcing, they should fit together. Consider Western solomn affairs, where as much dignity as possible is restored to the deceased. Kind words and remembrances abound, and the nasty business of actually dealing with the corpse is largely out of sight - if you see the deceased, they've been beautified to the point where they look almost alive. We encase them in wood to hide the result of burial or burning.

So - how do your people ritually grieve? What marks the passage into and our of this world, for them? The same applies to any ritual - it should reflect the religion and mythology you've created, the culture and the history. Don't feel you have to just leave it there, either - if you have a heavily spiritual people, they may well mark other occasions that are inconsequential to us. A more secular people may have fewer - or more. Rituals aren't necessarily about religion (though they most commonly are) - even a culture that doesn't believe in the afterlife has to do something with their dead and their grief. Look at what your culture believes and values, what their history is, and work from there. Don't miss the opportunity to show the reader your world.