Always bring cash for a date, and then bring some more. Plastic is prone to problems. Maybe the establishment doesn't take your brand of plastic, maybe there was an error at the bank, maybe you forgot how much scratch you had in your account, maybe you forgot to transfer money from your savings account, you see where I'm going with this.
Cash allows you to appear prepared, and women love prepared. It's a fact.
To maintain the element of cool be sure to have an assortment of bills in your possession. A hand full of fresh matching hundo's or twenties smacks of having taken the money out for this specific situation, and thus is not something you handle regularly.
Remember, cash is king. And always bring some more.