The secret is to obtain one or more sets of practice exams, in addition to one or more good books. You can visit an online bookstore like Amazon.com to use reader rankings to help you pick best of breed books, but I recommend the A+ Training Guide and the A+ Exam Cram 2 (by Charles Brooks (TG), and James Jones and Craig Landes (EC2), respectively). Your best study plan is to begin with a thorough review of the exam objectives (available at http://www.comptia.org/certification/A/objectives.asp) to identify topics where learning, study, and practice are needed, then to use practice exams to assess your exam readiness. When you can beat the required passing scores of 515 (Core Hardware) and 505 (OS) by 10% or more--or 570 and 555, respectively--you'll be ready for the real thing.
Oh--and one more thing: make sure you have access to one or more PCs that you can use purely for learning and practice. It's one thing to read about this stuff; it's another to use what you read to practice and play with what you're learning. I strongly recommend you set up a small home PC lab for that purpose, and I urge you to use a machine that doesn't have to be running so you or your family can play games, read e-mail, or do whatever it is they use PCs for routinely. That'll keep you out of trouble when your machine is torn apart as you're trying to figure out how to put it back together or restore it to working condition again.
This was first published in April 2004