NEW YORK (MONEY Magazine) - Imagine being rejected for a credit card because you once forgot to return a library book. Or not landing a job because you were late paying bills while you were unemployed. Or finding you can't refinance your mortgage at a low rate because a thief (or your cousin) opened accounts in your name. All of these scenarios are outrageous, but none, unfortunately, are far-fetched.

Your good name, once something you could build and nurture face to face, is now analyzed by a computer and ruthlessly boiled down to a single three-digit number, your credit score. That score not only affects how much you can borrow and at what interest rate, it also drives whether you can get a decent rate on car insurance or a new job.

And as creditors routinely peek at your behavior with other lenders for an excuse to hike your interest rate to as much as 30 percent, or even cut you off at the knees, just one slip can be especially painful.

That's why being in control of your credit is arguably the most important financial move you can make. The good news is that there's plenty you can do to boost your credit score, keep identity thieves at bay and restore your good name--and, by extension, qualify for better credit deals and wow anyone who thinks a three-digit number sums you up. The story that follows will tell you how.

Step 1: Find out what creditors know