I've worked with 10+ startups, either directly, or via R/GA Ventures
. I focus on product marketing and growth marketing for category-creating companies.
A mentor at Apple once told me: "Apple is like a big luxurious cruise ship. If it wants to change direction, it can only turn a few degrees at time. Startups, on the other hand, are speedboats. They move fast, and make hard turns. Manage to hold on, and you'll learn a lot."