One framework that might help is to think of the high-tech upscale startup path as a series of inflection points that affect valuations.
Eliminating or greatly reducing product risk becomes an inflection point, so it turns your valuation upwards for the next round. That happens when the website or app is built, when the prototype is available and tested, etc.
So too, eliminating or greatly reducing market risk, or proving or validating product-market fit, these are also inflection points.They also pop the valuation upwards. That happens when you get real validation like early sales – Kickstarter is ideal, a great example, even if it isn't about equity, but presales. Depending on the business, early deals with channels or distributors might do the same for physical products, and early subscribers for some kinds of websites, or downloads for apps.
Sometimes eliminating team-related risks can be an inflection point for valuation. For example, the team needs some very high powered expert in the community or the CMO. Solve that problem and valuation goes up with a sudden change of the curve.
Getting the seed round, meaning some outsider with money and experience has validated the business, can also be an inflection point by itself.