This is advice for both guys and gals.
It's just a date....a meal, coffee, maybe a movie or some ice cream with a nice decent member of the opposite sex. That's all.
Ladies, this isn't a marriage proposal. Don't plan your name next to his or figure out who your bridesmaids will be. Its just a date. Just give it a date ---He may not be interested in more. You may not be interested in more. Give both of you the freedom to decide that after an evening (or two together). He owes you respect and a pleasent evening, not a ring and promise of marriage.
Additionally, don't be so worried about marriage that you don't allow yourself to evaluate the date and see if he is someone you want to see again. Sometimes girls are so glad a man asked them out and so excited to have some interest that they become more concerned with impressing him so he will stay than they do in seeing if he is the type of man they want to stay with.
Men, this isn't a commitment. I have seen situations where a man has pined over a certain woman for months, finally get the nerve to ask her out, and then are devestated when she doesn't want more than a date or two. While you have had a relationship in your head for months and thought the final step to making her "your girl" was to ask her out, this is all news to her. She did not know you wanted to date until you asked her out. My advice? As soon as you are interested, man up and ask her out. Don't spend time planning how you two will be perfect together before finally getting the nerve to ask her out. Then you will have HIGH expectations and be dissapointed if it doesn't work out. Also, you will probably have so much riding on this one date that you aren't yourself which certainly won't impress her.
Certainly, be intentional. Within a couple months of dating, let the marriage topic come up. Make sure he knows thats what you are looking for. Men, make sure the lady is looking for marriage too. This topic has come up in dating situations and I have had it go both ways -- he was looking for marriage in the near future (and was obviously dating me to see if I could be that girl) AND I have had a guy say he wasn't looking for marriage for a few more years. Both ways, its fair I knew and its fair he knew what I wanted. (sidenote: the man who wasn't looking for marriage yet is a great guy and we are still friendly today. I think this because we both were upfront with eachother and I didn't come in with expectations that dates = marriage).
Dates can be fun. (and I know, sometimes dates get old, you don't want a bunch of casual dates, just the right date -- but the only way to get to the right one is to keep getting out there and meeting new people and dating is one way to do that!) Enjoy dolling up. Enjoy a nice meal and good conversation. Notice the qualities in someone you find attractive and even essential in a mate (your date may not be your soul mate, but you may notice something great about him that you eventually love in your spouse!). Try to be a good listener and encourager. Practice flirting. Enjoy being treated like a lady. Develop conversation skills. Try new places.
He may be the one, and you may know fairly quickly, but give yourself the gift of just being allowed to date, not search for a spouse. You can have a lot of fun and develop a lot of good skills. Plus, then when you are surprised on a first date and find yourself thinking, "this is different, what if there is something here?", you will know that is a legitimate feeling because you don't think that with every man who buys you a drink.
So, have fun. Just Date.