When in the dating phase, two people are still trying to get to know each other better, so it's important for both parties to keep up their guards and maintain a good appearance. For men this involves wearing proper clothing. As tempting as it is to revert to more casual clothing after a date or two, this should be avoided.
A business casual outfit appropriate for whatever location the date is being held at is also appropriate for a date. Take a look at our other advice articles to see what you should wear to whatever type of location the date is being held at (restaurant, bar, party, etc).
For any date, the less casual end of business casual is appropriate. This includes a long-sleeved dress shirt, dress pants (light or dark, khaki or wool) and a belt, pair of shoes and socks that match. sport coats are not typically recommended unless the date location requires them. sport coats can give the date too formal of a tone that can detract from the romance.
Make sure your shoes are clean and polished
Try and wear something different than what you wore on previous dates
Avoid wearing a sport coat unless the date location/event requires it