Halloween is observed by following way.......
Passing out candy with tracts (booklets to show how Jesus loves everyone and how they can be saved).
Having teen rally that night and teach the dangers of Halloween.
Inviting friends over and watch a Jesus movie.
Dressing up with others as Bible characters and "Street Witness" (word of caution: only those who are strong in the Lord in this area and are lead by the Lord to do this, so that there will not be any hindrances from the enemy.)
Teaching  children the dangers of Halloween, then have a family Bible study and pray for all the children that are out there "trick or treating".
Having  a "PRAYER WARRIORS" meeting: pray against all the evil forces that are out, pray people will wake-up and find the truth out about Halloween and become saved. That all the children will be safe from any harm: (tainted candy, razor blades and etc...). Praying  for all the innocent people held against their will for human sacrifices and all the other deeds of the Devil on this night! 

Facts:

The Celtic priests who carried out the rituals in the open air were called Druids, members of pagan orders in Britain, Ireland and Gaul, who generally performed their rituals by offering sacrifices, usually of animals, but sometimes of humans, in order to placate the gods; ensuring that the sun would return after the winter; and frightening away evil spirits. To the Celtics, the bonfire represented the sun and was used to aid the Druid in his fight with dark powers. The term bonfire comes from the words "bone fire," literally meaning the bones of sacrificed animals, sometimes human, were piled in a field with timber and set ablaze. All fires except those of the Druids were extinguished on Samhain and householders were levied a fee to relight their holy fire which burned at their altars. During the Festival of Samhain, fires would be lit which would burn all through the winter and sacrifices would be offered to the gods on the fires. This practice of burning humans was stopped around 1600, and an effigy was sometimes burned instead.