Let the kind of date you’re going on help determine your wardrobe. This sounds obvious, but so many guys blow it.
For drinks at a bar you want to dress as you would for a casual-yet-elegant night out. Don’t wear anything you’d be ashamed to be photographed in. This means a decent pair of dress pants or hole-less jeans and a button-down shirt with a collar or a polo shirt. A nice pair of shoes or non-white sneakers (they better be new and stylish) is also a must.
No flip-flops. You are not Jack Johnson
For an evening at a nicer restaurant or event, dress as you would for an important job interview. (That’s essentially what this is.) The two of you are determining whether you have a future together and you want to put your best (dressed) foot forward.
When she thinks of you after the first date, she is going to picture you in your first-date clothes. Present her with an image she would like to see again and again.