Samhain (Oiche Shamhna) is the most important sabbat of the year.
Pronounced as "Sow-in by the Irish, as SAV-en by the Scottish and as
SOW-een by the Welsh. It is exactly opposite Beltaine on the Wheel of
the year. It is reckoned when the sun has reached 15 degrees Scorpio.
Samhain lies exactly between the Autumn Equinox and the Winter
Solstice. This is a Cross Quarter day.

It is known as "Samhraidhreadh" which means "summers end". Samhain is
the start of the Celtic "New Year". The Celts divided the year into
two seasons, which are summer and winter. The summer is governed by
the Big Sun (the sun) and the winter is governed by the Little Sun
(the moon).
This is one of the four Fire Festivals and is known as "Trinoux
Samonia." Originally this sabbat was celebrated for three days, the
day before, day of and day after.
It is the day when the God symbolically dies and the Goddess is in
mourning, though She knows that He will be reborn at Yule.
It is the Third and Final Harvest. A time for preparing for the
coming year. It is also the day of the Feast of the Roman
Goddess "Pamona".
It is the day that the Tuatha De Danann, realized their permanent
victory over the Fomorians.
Since this is the time that the veil between Annwn (the Underworld)
and our realm of existence, is at its thinnest, it is a time to honor
and connect with our ancestors. To some wiccan faiths, this means
direct descendants who have passed over. To those of us in the
Celtic/Faery tradition, this means the ancestral spirits and deity
that resides within the earth.
One way to honor this day is "Fleadh nan Mairbh" (Feast of the Dead).
Set an extra plate or two at the dinner table for visiting spirits.
Another way is "Bannock Samhain". Setting out cakes and milk outside
the door. This is also the time for the "Dumb Supper", a meal served
in silence in honor of those who have passed to the Summerlands.
Remember, this is not a time of mourning, but rather of rejoicing and
connecting with those that have gone before us. We do not conjure up
these visitors as a medium would do . But rather we invite them to
share the day/night with us.
This is also a great time for divination.
Roasting nuts in the fire and bobbing for apples are a couple of
examples of divination from olden times. Another traditional way is
to set a shirt on a thorn bush near a stream and see what spirit
comes along to fit it on. At which time you would make enquiries.
Some of the Celtic Deity that you may appeal to for assistance during
divination are; Oghma, Rosmerta, Baile, Beli, Coventina, Badh, and
Gwyn Ap Nuad to name a few.
The concept of the carved pumpkin came about from the belief, that
carving a scary face on the pumpkin and using it as a lantern as one
walked at night, would scare away evil spirits. Originally they were
carved out of turnips.
There is an Irish legend about an Irish lad named Jack. He tricked
the devil into climbing a tree and then quickly carved a cross into
the tree so that the devil could not get down. He then made a deal
with the devil so that he would not go to hell upon passing. But when
Jack did pass, not only was he barred from hell, but he was barred
from heaven as well because of the doings of his life on earth. Hence
he was doomed to walk the earth carrying a lantern to light his way.
Thus the Jack-O-Lantern was created.
Another custom is to light a hearth fire on this day and to keep it
lit until the first day of Spring as a way of honoring our spiritual
ancestors and deity. Originally, all hearth fires were extinguished
on this day and then relit from the Druidic fire which was lit
at "Tlachhtga". This fire represented the center of Ireland.
Leaving a candle in the window as a beacon for spirits is also
customary.
Samhain is a time for reflecting on the year just past and preparing
for the coming year. One way to do this is to write the weaknesses
and negative actions of the past year down on a piece of parchment.
After a period of reflection/meditation, burn the parchment in the
cauldron or hearth fire. In this way you are starting out fresh for
the New year.

Some of the foods associated with Samhain are; pork, corn, apples,
pomegranates, pumpkin pie, and cider.

The colors associated with this day are; red, orange, yellow, brown
and black.

For incense, you can try basil, lilac, clove, yarrow or frankincense.

Some plants or herbs are apple trees, sage, mugwort (divination), and
gourds.

Some crystals are onyx, carnelian, and obsidian.