Plan a date where you DO something together. Play air hockey. Go bowling. Find a rock-climbing gym. It's better than sitting across a table and searching for conversation.
Don't apologize for anything unless you've done something harmful. That may sound obvious but it's a big thing for me, as I tend to be self-conscious and can end up apologizing for talking too much, talking too little, being too assertive, not being assertive enough, for having too little dating experience, for having too much, etc.
Ask questions, but don't just ask questions. You want to be interested in the other person but you don't want to turn the date into an interrogation.
Don't rush to fill every silence. When I forget this I start saying bizarre, inane things (like, "Carrots are weird. They're sweet when you cook them, but they're not sweet when you don't cook them. Carrots are weird." I swear, I heard the words coming out of my mouth and I couldn't stop them.)
Be ready with a cute, mildly embarrassing story about yourself that you can tell with a sense of humor. This can make you seem funny and confident without coming across as arrogant.
Remember that you're not perfect and neither is he. Don't beat yourself up for being a little awkward (if that happens). Remember that a facade of smooth perfection is less attractive than goofy, sweet, good-natured authenticity.
He's not going to be who you hope he is. No one ever matches the expectations we have in our heads, especially when we barely know them, so don't hold tight to those expectations -- they'll prevent you from appreciating the good qualities you didn't know he had.
If you find yourself still worrying about making a good impression, remind yourself that you're not there to make him like you; you're there to find out if you like him.
DISCLAIMER: These hints are based on my own dating issues. They may not be useful at all for anyone with a different set of issues.