You don't need a great first impression. Just about any great impression will do.
Many relationships and partnerships start out turbulent. It might take a while to find commonalities, maybe the right occasion doesn't show up for a while. If you can pull off a solid impression, even if its not the first, you will be remembered. Because people care about your potential. Even if you seem serious all the time, let them see you smile like a child just one time. And they will remember.
When you show your potential, they will want more, people can even get addicted to you. Imagine a time when you ate a chip or a cookie and said it was the only one. Sooner or later, you start craving and eating more of your snack. The same happens when someone takes a bite of your intriguing childlike self. They start craving your energy and company.