Ask HN: Recommended metrics/data-driven tools for smallish userbase?

I am starting to take an interest in data driving some apps that I'm working on, but am wondering what techniques and tools might be applicable to a relatively small userbase (a few thousand accounts). I am a believer in metrics-driven design, but I'm curious to hear what folks experiences have been in applying these techniques to small data samples.

If you have some recommendations for blogs or articles to read, or links to projects to check out, that'd be great.

I promise to give back by writing articles about my progress after trying out some of your recommendations.

EDIT: To give a bit of background, currently I have two main areas of interest: 1) Testing out and iterating on a new design for a site that has been historically a bit rough around the edges, 2) Starting the data-driven process as soon as possible on a couple new projects that are just beginning to pick up steam.