Get a Second Date

"I thought we would be spontaneous tonight." Let's not and say we did! That's what your date will be thinking the whole time while they're steaming about how ill prepared you are for the evening. It's not unreasonable for your date to have the expectation that you planned the evening. After all you're the one who asked them out on a date. It's usually a good idea to make sure you have a properly planned evening for the date and not leave things to chance at the last minute. At the last minute you'll often find that restaurant had no available reservations, the movie times didn't match, and the ticket to the event has already been sold out.
Trying to advance to 'coupledom' to quickly
It's just a first date, not a binding agreement to a lifelong of activities and matching clothes. There's no sense in talking about all the things you can do together as a couple because you've yet to spend enough time together to decide if you want another date, let alone if coupledom is right for you. Just like you have to learn to crawl before you walk, and walk before you run, you have to learn to go on a successive amount of dates before you can begin to talk about being a couple...or sharing food. It's still me and you...not we and us.
Talking or comparing your date to your ex's
Nothing will get the ire of your date more than if you compare them to your previous relationships. Behind that polite laugh and fake smile is a cold veneer just hoping you'll compare them to your ex again so they have permission to rip out your tongue with your fork. Anger aside, lamenting about your ex is in poor taste and poor judgment. There is a reason why you call them your ex and in its best to keep that part of your life in the past and enjoy the person in front of you. Even if they don't laugh at your jokes like your ex did!
Making your date the butt of every joke
Everyone likes a good laugh, but not necessarily at their own expense...all the time. If you're the type of person that enjoys telling a joke or two, remember the object of a joke is to have your date laughing with you and not about you. So it's always good to make fun of yourself first, before you attempt to make fun of your date.