Don't get a whole new card unless you plan to keep it for awhile, because the age of your credit helps you, and if you add a new card on, in the short term, it will bring your credit age down, and therefore your score down. If you decide to get one, do it to either get a better interest rate for the long term, or to get rewards that you will bank and use in the long term, but just know that in that scenario, in the short term, it might bring the score down. It is a good idea if you're playing the long game, though.

Examples when this might happen: you get engaged and want to go on a honeymoon in a year or two. You could get a travel card, and make loads of purchases through it, paying it off as you go, and then accumulate travel rewards to a free flight on that honeymoon.