Celebrated on October 31, the same day as Halloween, Samhain is when the veil between the worlds is at its thinnest, so it is a good time for scrying or to communicate with the spirits of loved ones who have passed away.
If you are a solitary witch, then a good ritual that can easily be conducted alone is suggested by Kate West in The Real Witches' Handbook. It involves meditating on the past and looking towards the future.
Light a black candle to represent the year that has gone, then spend a short time thinking about what has happened over that time, in particular remembering anyone you know who has died. Then, light a white candle and contemplate what you would like to achieve over the coming year. After that, do a divination for yourself and your loved ones, using whatever method you prefer, such as tarot cards or scrying into a dark glass or bowl of water. Finally, have some food and drink in honour of those who have passed away and to celebrate the season.
If you do not feel like taking part in a ritual, you could mark the day by visiting the grave of a loved one or a pet who has departed. Spend some time talking to them - the veil between the worlds is thin and you may just hear them answer you.