I'd recommend that anyone interested in startups download a capitalization table (Google "cap table download" without the quotes for a variety of choices), and just play with different scenarios. Plug in rounds from companies on Crunchbase (not just super-successful ones) and see what kind of money the founders are slated to get. See what happens if you don't meet expectations and go through a down round. It's better to see these possibilities before you're financially and emotionally invested in a company going through one of them.

If you still believe your startup idea is a slam-dunk after seeing how horrible things can get if there's any hiccup in the process, then you're ready to take an investor's time to give a proposal.