Most Helpful Girl
Well don't blurt out "I'm looking for my future wife!" because you will put too much pressure on her, and it might make the date awkward. However, it is perfectly OK and a good idea to mention that you are looking for a serious relationship. I would just leave out the marriage part, unless she asks you about it. Always be honest and be yourself...otherwise you won't find what you're looking for. Ask her questions about what she wants and what she's looking for...you'll be able to tell if she's on the same page as you. Girls who want serious relationships will appreciate your honesty. The ones who don't want to be serious, or who are unsure, might get freaked out but at least you will know not to waste your time.
First dates should be about having fun and seeing if your personalities click. Focus on having a good time and getting to know what her interests are, etc. See if you two have anything in common first. If the date is going well and you like her, then maybe casually ask her what she's looking for (serious relationship, a fling, just a good time, etc) Don't worry, you'll find your perfect girl soon!