But I think the most important date; formal or informal, dinner or something more active - whatever; it's important that you are comfortable. So if you're normally a jeans and t-shirt type of person go for something like that, just dressed up a little; stick to your normal style - if you've been asked out or been accepted for a date, he clearly likes what he sees. Just put maybe a little more effort in than everyday - not too much though. Comfort and confidence are the key things, and it's hard to be confident in something you're not comfortable in.
Whatever you want. Don't be fake and dress up. Dress how you would normally dress if you went out shopping, or to just go out in public. Not much thought is needed for this. Waaaaaaaay too many people get to crazy with this. It's none sense. Be yourself.
if the dtae requires a dress then go with the 40% rule, pick an outfit that only shows 40% of ur skin, because it compliments ur assets and leave a lot to his imagination ;), and I do swear by the LBD on first dates