I'm starting to unify much of my marketing around a set of core metrics.
There are five general categories:
I then adapted them for Repeat Customer Insights to fit its business model (subscription software as a service):
- Traffic became Total traffic
- Leads became App installs
- Conversions became Trial completions
- Retention became Revenue churn
- Revenue became MRR
This gives me a basic marketing funnel which I can evaluate and improve on. For example, is Traffic high enough? Are Trials Completing are abandoning? etc, etc.
Each metric will have associated sub-metrics while I'm working on them, but I won't bother worrying about those sub-metrics most of the time. That means if I'm focused on Total traffic I might be measuring my organic traffic for SEO, who referral sources are, or how advertising clicks are performing. I won't worry much about App installs, trials, or negative churn.
At least until I shift my focus away from Total Traffic.
This sort of setup helps keep the number of active metrics manageable. There's more metrics you'll want to be collecting all the time, but you can save most of them for later optimizations (historic views, trends, etc).
Based on this framework, Repeat Customer Insights analyzes the data for the latter three: Conversions, Retention, and Revenue. Retention is its main focus but Conversion (orders) and Revenue naturally comes out of much of the analysis.
Google Analytics can work very well for the Traffic and Leads category (maybe supplemented with an abandoned cart system and email system for the Leads).