1. Don't get too excited
This includes to not talk nineteen to the dozen or twitchy sliding from the one half of your chair to the other. Take a deep breath and relax.
2. Never ever talk about your ex
Suprise, surprise. This is a no-brainer, but some people are so enamoured by their ex that this topic always comes up. Don't talk about any past relationships unless your date asks you explicitly about it. You just sit here with a person you want to get to know better; the past doesn't matter now.
3. Being on your phone all the time
We've already mentioned this before. It's impolite and creates the impression that the date doesn't matter to you.
4. Only talking about yourself
Nobody likes selfish people. Try to get a balanced relation of your talking parts. Ask questions and be interested.
5. Playing hard to get
This could backfire very fast. Misunderstandings will make the process of getting to know each other interminable and building a healthy relationship harder.
6. Too many compliments
By giving too many compliments, you will simply overstrain your date. If you give a compliment, choose wisely if it's appropriate and honest.
7. Asking "What are we?"
Not. Yet. It's just your first date, so the answer should be clear. You are only two people who are interested in each other - everything else will evolve later.