The deal isn't done until you get their John Hancock (and the money is transferred).
For a hot deal, the dynamics of a fundraising round can be very unpredictable. If the company has several offers, it'll probably come down to a board vote. Engage every board member so they're aligned with the value your fund brings to the company. Very important (and painful) lesson - I learnt this the hard way.
Avoid FOMO / herd instinct / groupthink, and try not to fall in love with the wrong companies.
Take what others say with a pinch of salt. Don't let yourself be ruled by the emotions of a round. FOMO is completely irrational - you'll never lose money by not investing. Before you run off to your Investment Committee to propose investing in a company "because that McKinsey report said the market is..." and "because investor XYZ has agreed to join the round", think through the fundamentals of the business. Who is running it? To whom does it sell? How does it distribute? Why is it defensible? Does it make money on a per-unit basis?
Be honest, fair, empathetic and responsive towards entrepreneurs.
It's an absolute privilege to work with entrepreneurs - also known as the subspecies of humans who are smarter, braver and more driven than most of us. I still find it weird saying "no" to entrepreneurs who are probably smarter than me and have life+work experience that's a multiple of what I've experienced. But it's part of the job. Do it right without leaving a sour taste in their mouth. Treat them with respect.
Be conscious of the power you wield
As a VC, you must be mindful of the impact you could have on the future of humanity. You decide which markets will be disrupted. You decide which jobs will be created or destroyed. You decide which technology gets funded. You decide which products get to the palms of the consumers. You decide how society will be shaped. You're also spending and investing the wealth of others (your Limited Partners or LPs): pension funds, high net worth individuals, family conglomerates, etc. Be conscious and be responsible.
Everything can be learnt. If you want to.
A job in VC is a job in lifelong learning. Grasping difficult concepts quickly is a huge part of the job. The fundamentals I've picked up in my first 5 months - deal sourcing, due diligence, term sheet, cap table, deal making, and board meetings - are relatively easy to learn. But this is just the beginning. Comprehending 3-4 business models per day, sniffing out bullshit entrepreneurs, grappling with complex technologies, reading reports with esoteric scientific terms, speaking with experts, attending numerous events, and answering to your LPs... these things will keep your mind buzzing. But there’s always more to learn and grasp. Get used to it. Buckle up and enjoy the ride.