QUOTE(J&K @ Sep 11 2007, 10:31 AM)

Actually, when you yourself check your credit score it has absolutely no impact. It's when someone else looks at your report and does a "hard inquiry" that it affects your score. Whenever you look at it, it is called a "soft inquiry" and only you can see them. Promotional inquiries also fall under the soft.
And as YuandDan mentioned, opening a new Tradeline does hurt your score, but after timely payments and keeping the utilization to about 35% or less, after 6 months the tradeline won't hurt you as much. After 2 years of timely payments and low utilization, the tradeline isn't considered "new" anymore and will greatly help your score.
Also, it's not how much credit you have that will hurt you, it's how much debt you have. Good debt is a mortgage or car loan. Bad debt are credit cards. You want to keep the utilization down low on them (35% or lower).
I have been repairing my husbands credit for the past year and half while building my own, so while I am no expert, I have been doing a lot of research on credit in the US.

I want this pinned!!!

I'm repairing hubby's credit too. And building my own

QUOTE
I realized if would lower the score, but it was the size of the hit I found astonishing.
It's a big hit indeed. When I opened a new credit card, it didn't affect my score at all (at least the Equifax score that I constantly monitor, I don't know about the other two). When I got a car loan, my score went up one point.
But I've also seen my score decrease by 2 or 3 points for no apparent reason, so I really don't know what to think any more. My personal observation: my score increased the most when lenders upped the credit limit on my cards. Each limit increase ~ +10 points.