Here are some thoughts...
Earning investment from an Investor is a lot like dating and/or forming any kind of relationship. Therefore...
Ideally, you're meeting an investor for the first time BEFORE you are raising capital.
Do some research into what they care about - both personally and professionally. But don't be a stalker.
Get a warm intro through their network.
Get them excited about your company through a combination of voice and vision. Show your passion and explain why this is a big idea with big potential to make the world a better place.
It's likely that you don't have much built yet - so they will essentially be investing in YOU, not your idea or company. You need to convey a sense of personal credibility and conviction while still demonstrating that you are coachable and collaborative. This means you should be able to...
a) Be clear and straightforward about what you know, your hypothesis and what you're still yet to figure out. It's ok that you haven’t figured certain things out yet - but its important to know and admit it.b) Avoid absolutist language and scarcity thinking
c) Both eagerly hear and digest ideas/criticism while also defending key decisions or beliefs you have - all without being defensive.
d) Earnestly ask for and capture feedback and advice. In particular, ask what the investor would need to get conviction about your company when you come back while raising a round
e) Compensate for any weakness in your background or skillset by having pulled together a great advisory and operations team, a strong pitch deck with a clear narrative, and a beautiful product. Or better: Lots of traction!
Set good expectations about what you're going to do next with the company - including responding to or acting on their advice and requirements to invest - and be prepared to come back having delivered on those things (or have good information about why those things were no longer relevant).
Focus on finding a fit instead of convincing them of something. After all - you have to live with them as a partner in your business. You need to like each other!
Relax