1. Know your value
If you have a real product that solves real problems for real users and it has growth and retention - you are already incredible.
Believe in yourself and the value of what you've created.
Even if you don't have the above, understand the value of what you've derisked in your startup and feel confident it's worth what it's worth at that given stage.
2. Know the value of other things
Remember, this is not a bank loan. It's not about how much you can afford. It's about how much your company needs to win its category. They are not lending you the money; they are BUYING part of your company.
Remember that the money you think is BIG money is NOT that big. There is basically infinite money in the world. It needs to find a home. Billionaires and millionaires spend millions in holding costs for their Yachts each year. They park money in fancy homes because they have nothing else to spend it on.
Many VC funds have 10s and 100s of millions of dollars under management. They need to deploy big cash to just a handful of companies. That's their JOB.
More than any of that - they want to fund companies to WIN. You need to ask for a credible amount to get to the next major milestone in your company. If you ask for too little, you are undermining your case - not helping it.