Let's start with the shoes
In our casual society it may be perfectly fine to wear sneakers with a suit, but I do not feel that Frank Sinatra would have ever done so. Unless you are 17, just put on some leather oxfords, shine them and don't look back. These Paul Malone's are a good pick for almost any outfit
Black socks are perfectly fine and will do the deed. However, if you want to show that you are paying attention to every detail, try a good pair of patterned dress socks.
What about pants?
If you are taking your date to a ball game, by all means, wear dark Jeans and a T-Shirt. If you plan on taking her out to a nice dinner, wear a suit or at least suit pants. Dark colors such as black, dark blue or charcoal are always appropriate.
Button up, always! As mentioned earlier, your date won't be very impressed with your latest addition to your Star Wars T-Shirt collection, Make this the one day of the year to wear a clean, ironed shirt and TUCK IT IN!
The ultimate accessory is the tie. It makes an outfit stand out and upgrades your appearance. Show your date that you are paying attention to detail and match your tie to your shirt and suit (or sport coat). Pick complimenting colors and Pattern, possibly go with a matching pocket square. If you need help picking one, let us help you.
Dress to the occasion. If you are taking her out to the best restaurant in town, wear a suit. A more casual location calls for a sport coat.
The last and obvious
If your date goes well, don't get caught in less than stellar underwear. There are more options than the 12 pack of underpants from your local supercenter. Invest in good underwear.