Dress code for dating, be it first date or many times. it's all depends on the event.
Restaurant, or Bar
If you are taking your lady to a restaurant, a dress shirt is a must. Find a nice, collared shirt that is currently in style. You can find a lot of online resources such as a-man-fashion :P or maybe subscription of a Men Fashion magazine is a good start. Jeans work if the setting is casual, but dress pants may work better. The shoes you wear must be dress shoes. Minimize any fashion accessories.
Club
Most clubs have a dress code. So check the rules for the club you're attending. Most of the time a nice collared shirt is appropriate along with a nice pair of dress pants. Again, dress shoes are a must and if possible, minimize any fashion accessories that you used to carry.
Bowling, Mini Golf, Movie, Concerts, Sports event
This is the freestyle come into play. You could dress up for these events, but most likely you'll look like a dork. :( Wear a clean pair of jeans and a shirt that's in style. Hiking shoes are alright in these kind of environment, but if you can, wear darker in color.
If your date isn't familiar with the type of setting you will be taking her to, you will want to let her know the type of dress the setting requires. Let her know of your plan to wear jeans so that she doesn't show up dressed to the nines.
Use your best judgment based on the event, but keep in mind that you need to bump it up a notch if you want to impress. There is no "one size fits all" rule. Physical appearance such as comb your hair, brush your teeth, slap on the cologne are equally important.
Tags: Man Fashion, Men Fashion Tips, First Date, Dress code