Well, definitely opening up a line of credit can lower your score and then just transferring balances can also lower it depending on the balance and max withdrawal ratio (spending limit). You really never want to go over 50% your spending limit on a credit card. The longer you have an account, the better report they have for you on your spending habits and this is one factor that the bureau likes; longevity. It's actually sounding silly these days, but it is like you are almost paying for your credit score to increase by sticking with a credit card company that is charging you more than the other guy. It's all a silly game these days.