What you will need: a journal, pens, crayons, markers, and whatever else your family members need to express themselves.
As you choose or make your journal, keep in mind that it is going to have to endure being handled frequently by your kids for the next decade or two and when they're through with it, it is going to be handed down to their kids, and their kids, and so on. Splurge on a high quality journal that will last through the years. Check the binding to make sure that it is durable. Cheaply bound books often come apart after the first several times you open and close them.
Make sure that the pages are made of acid-free paper. You'll want fairly heavy paper so that younger children can use markers without bleeding through several pages. Choose a style that represents your family. Leatherbound books with tie closures are timeless and will look and feel like treasures. If whimsical colors and patterns speak to you, go that route.
You can also make a journal. Many craft and scrapbooking stores offer classes on book making and paper making. Some families keep a journal in a scrapbook-style book that they can add pages to. If your family keeps up the journal writing tradition, you may go through a few journals before your kids grow up and leave home. If that's the case, you can keep the journals looking consistent, or do something completely different with each new journal.
Getting the Whole Family Excited
Keeping the journal should be a fun activity, not a chore. A good way to make sure everyone is well represented in the journal is to set aside a time every week when everyone is together to write entries. Ten or fifteen minutes as you're wrapping up family home evening is a good time. A weekend night right before bed works well too. By taking turns every week instead of having everybody write in it all the time will help keep it fun instead of having it become a chore. This way, every member of the family gets a turn at writing every few weeks depending on how many people are in your family.
Journal entries don't have to be written in first person prose. The purpose of the journal should be to let everyone's talent and creativity shine. It's good to have Mom, Dad, and older writers keep a more accurate record of the things that are going on in the family, such as important events and milestones so that future readers have a good idea of what is happening at the time. However, poems, pictures, doodles, comic strips, short sentences, paragraphs, and single words are the things that will truly capture an individual's personality and capability.
When it's your baby's week to write in the journal, let him hold a marker and flail his arm around on a page. Write his name and date in the corner. Next week, let your toddler try to write her name or draw a picture of the family. Let your teen keep a running comic strip or poetry column. Giving free reign to kids makes the project fun instead of tedious.
Preserving Your Journal
After you've kept a journal for a while, you'd be devastated if anything happened to it. If there were a fire in my house, the first thing I'd grab after I made sure the kids were safe would be our journals. I highly recommend using a scanner to upload images from your journal to your computer regularly. This way, if something does happen to the journal, you'll still have scanned copies of everyone's original handwriting and artwork. Burn the images onto a CD and store them in a safe place or at relative's homes so that if your computer crashes or gets stolen, you'll still have a copy.
Whether your family size is ten or two, whether your children are in nursery or nursing their own babies, all families have one thing in common: memories. With a little creativity and a lot of fun, you can record those memories in a family journal that the whole family will cherish for years to come.