You are entitled to 1 free report from each bureau each year... this can be obtained at
http://www.annualcreditreport.com - this is a co-op project between all three credit bureaus and will let you quickly and easily check your report.
There are two types of "inquiries" soft pull and hard pull.
A soft pull is when a bank surface scans your report to send you promotional offers and other nonsense (pre-approval for loans, credit cards, insurance etc). These "soft pulls" of your report are not calculated into the math that comes up with your credit score
The other type of inquiry is called a "hard pull" or a true INQUIRY. This is when your entire report is pulled by an agency in order to determine whether or not to grant you credit. ie, applying for a car loan or looking to refinance your home. These HARD PULLS negatively affect your credit because they indicate that you are looking to aquire new debt. you are looking to take on an additional finacial burden (a new credit card, a car loan, etc.) If you have several pulls that are spread out over time with no NEW accounts being issued then it appears that you are frantically trying to obtain credit and because no one has granted you credit yet, that you may infact be a risk... this puts your score lower.
Your creditor score is nothing more than asessment of risk. It is a quick way for creditors to determine if they will get their money back from you.
Any time there is activity on your accounts it affects this number. You would be surprised to see how often your score will fluctuate... From month to month most people's scores with go up or down a few points.
One way to limit the damage of a HARD PULL inquiry is to do all of your searching in a 2 week timeframe. You can have 4 or 5 HARD PULLS in a 2 week period and it will only affect your score as if you had 1 HARD PULL.
I hope that clears things up. Oh, one more thing - YOU pulling your report, has ABSOLUTELY no affect on your credit score- it is a stupid myth like "cola dissolves steak." you can check as many times as you want without damaging your score (but you cant check it free of charge more than 1 time per year)