Here are my 2 cents:
When you have product/market fit -> you'd do the 'traditional' thing - ie Gartner reviews, trade shows, marketing etc - All that requires big money - significant investment
The interesting part though is when you are in the early/seed stages - and that's the hard problem to solve for. You are iterating, trying different things - perhaps testing different verticals.
The way we've solved that at Kormox is doing it through 'insiders' - we'd build a spreadsheet of target companies (say 300, focused on a specific vertical), then identify who we'd want to talk to (say, Johnnh Smith, CIO) - then, identify internal people in the company that have nothing to do with the CIO but you have a good change in getting 10 minutes of their time. We particularly used alumni networks - e.g. Wharton, McKinsey, Stanford GSB, etc etc.
Then you reach out to those insiders asking for 10 minutes of their time - not to sell anything, rather to get their advice/pick their brain on how you can reach out to relevant person to get opinions on your startup (you can mention you think Johnny Smith would be the right person).
It has worked really well for us. Typically those insiders would do an intro - and Johnny Smith would be happy to meet with you in that way.
We've been able to do this at scale pretty successfully.