A 3-by-5 corral for all those little details you need to remember

Years ago I learned a most practical yet simple secret of household and memory management: a small spiral notebook, always kept in pocket or purse. One section of my notebook is devoted to clothing needs. Like many parents, I sort out each child's garments twice a year, deciding what pieces still fit or can be passed down, and what I must buy. In the notebook I then add, ''Nancy - white blouse (size 12), jeans (boot leg)'' or ''Brian - pajamas, winter coat, red sweat shirt,'' on a shopping page.

The list is not likely to get lost since it's part of a book that's always in my possession. And it's not only handy for planned shopping excursions, but invaluable if I find myself in the midst of a wonderful sale. I don't have to wonder if anyone can use those half-price sweaters or if I'm buying them for a child who already has several. When the clothing list becomes dated, simply tear it out and start again on a fresh page.

I've taken the clothing list a step further by also keeping a record of items I'd like for the house. These aren't things that are purchased on a regular basis, but items that I might think about at the moment, then forget. Have I, for instance, considered buying a wicker planter for the front hall? Are we getting low on candles, washcloths, photograph albums? Do I someday want to buy a decent carving knife? It's easy to remember some of these things, but if one comes unexpectedly upon a good store special or garage sale, a ''someday list'' can fill in the blank spots in the memory.

Many notebook devotees also include a page or two of gift ideas. How often have we heard a relative or friend express an interest in a certain brand of needlepoint yarn or scented soap, only to forget the comment later? Have we watched a preschooler play happily with an unfamiliar toy at a friend's house, or heard an older child wish for a special game? Although children's tastes change quickly, such comments can be easily added to a notebook, then reevaluated when gift-giving time approaches. A gift page also makes Christmas shopping easier by providing ideas all year round.

Additional pages of a small notebook can be used for any organizational purpose. One of my friends, concerned that her family might be spending too much on clothes, logged each purchase in the back of her notebook all year, and found it much easier to keep track of than charge slips or checks. Another keeps a list of books she'd like to borrow from the library, culled from published reviews or comments from friends.

A notebook doesn't take the place of an appointment calendar, but it does eliminate memos scrawled on bits of paper. It contributes to a sense of order and helps a parent remember the myriad details involved in raising children and running a home.

When the notebook eventually runs out of pages, it takes only a few minutes to transfer any permanent records to a new one - and start all over.