Some people, especially those with very few accounts, can open a CC and never have a dip, because their credit profile "needed" an additional account.
One thing you can do is to go to the sims on your current FICO EQ and TU reports and play with the options of adding a bank card, a retail card, a car loan, etc. If your current score is right in the middle of the projected score range, then it probably won't hurt you too badly.
But don't lose track of what will happen to your AAoA (average age of accounts), plus the newness ding, which can be very real indeed.
I find that usually my scores are about where they were 3 months after a new account, except for a longer recovery period on my app-o-rama in February. Still, the scores are all recovering, and it's been 6-7 months.
* Credit is a wonderful servant, but a terrible master. * Who's the boss --you or your credit?
FICO's: EQ 781 - TU 793 - EX 779 (from PSECU) - Done credit hunting; having fun with credit gardening. - EQ 590 on 5/14/2007