The simple charms of a homemade Christmas

''Snow is falling in a quiet and serene natural setting. Inside the house, a fire glows in the fireplace . . . the only holiday decorations are a Christmas tree, candles, greens, and simple homemade decorations. Christmas presents, if there are any, are inexpensive remembrances, or intangible spiritual gifts. The family members are in a good mood and enjoy each other's company in simple ways, like taking walks or sleigh rides together, or gathering around the fire to sing carols or play musical instruments.''

That picture typifies a traditional Christmas celebration for many Americans, according to two researchers who have been conducting interviews throughout the US for a number of years.

Jo Robinson, co-author with Jean Staeheli of ''Unplug the Christmas Machine: How to Have the Christmas You've Always Wanted'' (New York, William Morrow, $14. 50), says the core of this ideal - simple gifts, natural decorations, traditional foods, leisurely schedules, and family activities - is well within reach.

''People are so ready for a simple Christmas this year,'' she noted. ''Because of the financial climate, they're finding that they can't go out and buy Christmas - they have to make it for themselves. And that usually means taking 10 minutes to sit down and decide on the one thing that's most important to their celebration of Christmas and then finding a way to bring that closer.''

Nineteenth-century Christmas celebrations often continued through New Year's Day with a wide range of family activities - parlor games, dancing, music, sleighing, caroling, and masquerade parties. Today, with more women working outside the home, with smaller families, more single parents, and more people living alone, holiday traditions often require some rethinking and retailoring. But by alternating favorite projects from year to year and scaling down social obligations, the authors say, people can learn to enjoy the season more and make it last longer.

What follow are dozens of suggestions the authors have collected over the years.

Activities for children: To make the season last longer, many families minimize gift-giving and promise children special activities to look forward to both before and after the opening of presents:

* Make a family calendar for the month of December with pictures of things that are going to happen on specific days: Draw a pine tree on the day the Christmas tree will be purchased or pencil in airplanes on the days that relatives will arrive and depart. Set specific dates to look forward to - Dec. 15: Put the wreath on the front door; Dec. 20: Set up the tree; Jan. 1: Have a potluck dinner for friends and their children.

* Make the morning of Dec. 25 special: The first person up that day puts his or her favorite Christmas record on the stereo and cracks a bowl of nuts for the rest of the family.

* Celebrate the 12 days of Christmas with activities for each day. Have a ''kids-choose-the-menu day,'' a ''hear-a-story-as-many-times-as-you-want day,'' and a ''grandmother day.''

* Open Christmas cards at the dinner table, taking time to look at the illustrations, to listen to the messages enclosed, and to talk about the friends and relatives who sent them.

* Begin opening gifts by reading the Christmas story from the Bible in the book of Luke. Open presents one at a time, showing young children photographs of faraway relatives who have sent various presents.

* After the gifts are opened, give the birds a Christmas treat by decorating a tree in the yard with strings of popcorn, rice cakes, and hard rolls.

* Buy a jigsaw puzzle or new board game for the day after Christmas.

Decorations:

* Set aside time to select the Christmas tree and decorate it. Assign everyone a task by reserving certain ornaments for children to hang and by making the hanging of the star a privilege.

* Encourage everyone to contribute at least one new inexpensive tree decoration each year.

* Give each child an ornament for a present each year. Collect ornaments on family vacations. Choose ornaments to represent important family events - a new baby, a new house, graduation, a new job.

* Use evergreens, dried flowers, weeds, cones, leaves, and corn husks in wreaths or in vases for a table centerpiece. Outline doorways with evergeen garlands and decorate indoor plants or trees with ornaments. Place a stem of holly on dinner napkins and use holly to decorate wrapped packages.

Traditional foods and dinner:

* If the women in the family have always cooked the traditional Christmas brunch, try switching roles. In one family, the husbands took over, offering grilled trout and pancakes, while the children set the table, made the centerpiece, and drew hand-printed menus and place cards.

* Begin Christmas dinner with a special ritual - a prayer, candle-lighting ceremony, or just a few quiet moments holding hands.

* Ask family members to bring old photographs, diaries, heirlooms, written anecdotes, and genealogical information to the dinner. After dessert, tell family anecdotes: Who knows the earliest one? Is there one that's never been heard before? How many versions are there of the same story?

* To make the preparation of holiday food more enjoyable, involve more people. Invite friends over for a taffy pull; plan meals guests can make themselves, like tacos; plan a tasting party, with each guest bringing one dish; organize a progressive dinner; issue spontaneous invitations.

Gift giving:

* Give presents to young childen only.

* Take children grocery shopping for food for local families in need.

* Put all family names in a hat and have each member pick one person to give a gift to.

* Draw names from a Christmas stocking and do things throughout the year for that ''secret pal.''

* Give handmade or service gifts - a walk, a shared meal, a phone call, a letter. Single parents: Fifteen percent of all American households are now headed by single parents, many of whom have told the authors that Christmas is one of the happiest times of the year.

* Encourage children to spend time with both parents, and make travel arrangements well in advance.

* Initiate new traditions. One mother, who had always served a traditional Christmas Eve dinner for eight, gave her two daughters the option of takeout pizza that night - a tasty success. Another mother invited all the single women she knew and their children to a three-day celebration and slumber party.

People alone: More than 17 million Americans live alone, and while many travel over the holidays to be with relatives or extended families, many also choose to spend the time by themselves.

* If you're planning on a quiet holiday, set aside time for prayer or meditation, for hiking, skiing, or camping.

* Save up special reading material for Christmas Eve and Christmas Day, prepare your favorite meals, and play your favorite music as long and as loudly as you like.

* Bake banana bread and take it around to neighbors on Christmas morning.

* Reserve a cabin at the beach or in the mountains for a few days at Christmas, then throw a big New Year's Eve party for friends when you return home, to balance the solitude.