First impressions matter, and they matter a lot.
Do your homework before meeting someone new. Prepare 2-3 talking points before you are introduced. Talking points should showcase your expertise, demonstrate strong perception of context, and show that you can discriminate between what matters and what does not.
Ideally the points will come up organically during the discussion, but if you get to the end of the conversation, and they haven’t emerged you might say something like, "Before we leave, there are few things I want to make sure I mention."
It is normal to be nervous when meeting new people but you don't want your anxiety to show. Your body language should be confident and comfortable.
Record yourself. Become familiar with how you look and sound. Make adjustments until you like what you see and hear.
Know what you are good at (the domain of your expertise), and prepare evidence of your expertise. What objective measures can you point to as evidence of your mastery?
Find genuine connections. They don't need to be profound or breathtaking, they just need to create a sense of commonality.
You are not trying to make a good impression with your vast knowledge. That approach is a mistake. Your aim is not to "wow and dazzle." Rather, you should create a conversation that is memorable and meaningful.
Even when the conversation is over, your job is not finished. Follow up on any commitments. To ensure your first impression sticks, it’s wise to write a personalized note, reach out on LinkedIn, etc. You want to show that your conversation had an impact on you, which in turn makes an impact on them.