Here's some advice if you're shopping for a last-minute gift for a computer user or if a new computer shows up under your own tree and you want to take advantage of post-Christmas sales for goodies to enhance it. These products are not the fanciest or the latest, but they are all tried and true values.

Everyone needs a printer, and the best buys these days are in 24-pin dot matrix models. An outstanding value is the Panasonic KXP-1124. You can get it for $300 or less and it generates excellent letter-quality text. In addition, it lets you insert individual sheets through an opening in the front without removing the fanfold computer paper fed through the rear.

Among portable printers, the Diconix 150 Plus inkjet, about $350, is the market king. It's small -- about the size of a hardback book -- weighs less than four pounds and turns out high-quality text.

Another worthy inkjet printer is the Hewlett Packard Deskjet Plus, about $500. It provides output similar in appearance to that of a laser printer for far less cost. It uses stacked individual sheets and automatically feeds them. The deskjet is roughly the same size as a dot-matrix model.

Another useful device is a modem, and they have become remarkably cheap. You can get a good 2400-baud internal modem (a board that fits in an expansion slot inside your system) for about $125. A comparable external model costs about $50 more.

You need software to drive your modem and the best value is Procomm Plus, about $60. It is easy to use, yet full of features. If you prefer to try before you buy, you can order the shareware edition of Procomm (version 2.4.3) from a software library.

Speaking of those libraries, one of the best is the Public Software Library, P.O. Box 35705, Houston, Tex. 77235. Phone: 1-800-2424-PSL. Nelson Ford, who runs PSL, publishes an excellent newsletter for $18 a year.

For those to whom the world of modems and shareware is of special interest, consider Dvorak's Guide to PC Telecommunications, about $50 at most computer book stores. This hefty paperback comes with a pair of 5 1/4-inch disks that contain a generous sampling of author John Dvorak's favorite shareware programs.

Included is a powerful modem program called Telix SE, similar to Procomm. The book tells you all you might want to know about modems, computer bulletin boards and on-line data services. It's not for the casual user, but for the enthusiast, it's a treasure chest. Should you need to special order it, the publisher is Osborne McGraw-Hill.

For spreadsheet number crunching, Lotus has a good deal. It is offering version 2.2 of the famous 1-2-3 spreadsheet with the very popular personal-banking program Quicken added in free. Lotus 1-2-3 is the king of spreadsheets and version 2.2 is the latest edition that will run on all PCs. Quicken will not only keep track of your bank accounts but will also write your checks. You may need to hurry because the offer officially expires at the end of the year, but some dealers may be willing to extend it.

Among word processors, the industry standard is WordPerfect 5.1 (about $250). It's powerful but difficult for new or occasional users. The ideal companion is Ko-Pilot, $79.95, from Insight Resource, 175 Prospect Ave., Tarrytown, N.Y. 10591. Phone: 914-332-1589. It installs a set of training wheels in the form of extensive menus and it posts help messages on the screen to guide you through WordPerfect's many functions. It makes you productive with WordPerfect right away.

A less expensive option is PC-Write Lite, $50, from Quicksoft, 219 First Ave. N, No. 224, Seattle, Wash., 98109, 206-282-0452. This lightning-fast program is a slimmed down version of the shareware classic PC-Write. It has robust editing power, plus such added features as macros, footnotes and spell checking. Because it's shareware, you can order just the disks for $12 and give it a try. This program can be configured so that it only takes up 150K of storage space, making it especially well-suited for laptop systems, many of which don't have a hard disk.

You may have noticed nothing has been said here about Microsoft Windows, the hottest product in the PC world. That's because it doesn't run very well except on the most powerful systems -- those with at least a 386SX processor and two megabytes of memory.

Those with less power might do better with Microsoft Works, a smoothly integrated package including a word processor, spreadsheet, database and communications program. It provides some of the look and feel of Windows and a full set of applications as well for about $100.

Brit Hume is a contributor to the Washington Post Writers Group. He is chief ABC News White House correspondent and the founding editor of a computer newsletter.