I don't think I would add anything to Sean's pyramid but I do have my own approach to things that essentially breaks it down a bit more to a granular approach.

1. Find users who've had success

If you're lucky to have 100-1000 users, I'm hoping you can identify 5-20 of them that love your product or had success. If so, then study them. I always suggest trying to understand what "path" they took when signing up for your product, in what order, and see if there's commonalities. Find them, then change the way you introduce (onboarding) your product to new users so they all experience the "a ha" moment those users discovered.

2. Test the size of the market

The biggest challenge I see with startups is that they spend 99% of their time iterating around the product, and 1% thinking about the market. It's called product / market fit - so spend time understanding if you're product actually addresses the needs of the market. If not, maybe try a different market and see if it sticks. Many times it's not the product, it's the market you're trying to serve that doesn't have a real "must have" desire.

3. Identify your growth engine.

Eric Ries described it best in his book The Lean Startup, but Lars does a good job recapping it here: http://larslofgren.com/marketingbasics/the-three-engines-of-growth-with-eric-ries ... don't fool yourself in believing that you have some new / unique distribution approach. Find the growth engine that describes you, and start iterating around those user flows.

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So in summary, not that I would add anything, but I would elaborate more on the mechanics of growth hacking then just talk high level at 30,000 feet.