One of the best ways to start practicing Lean Startup in real life is to analyze your current product and see which features are used:
by many customers
many times per customer
The idea is to take your current product, analyze feature usage and plot it on a graph.
The horizontal axis will consists of few/some/most/all customers using this feature.
The vertical axis will consist of this feature being used little/some/most/all the time per customer (e.g. this feature has been used 10 times on average by each user)
Doing this for every major feature in your product will create an "audit" of the features in your product and which are popular and which are not. The idea of a Feature Audit was given to us on the Intercom blog and is sometimes called the Intercom Feature Audit as a result of its inventors. You can see the Feature Audit graph structure below:
Intercom's Feature Audit
Where to Focus
Any features that are in the top right section of the graph should be your priority (see the green text in the graph below!). These are features that all of users are using (meaning they are all aware of this feature) and all of these users are using this feature all the time (meaning they see the value of the feature).
This feature is the core reason (or one of the core reasons) that customers love your product. If you can make improvements here, it will delight your customers - all of them. However, if you make a change and it is perceived badly by customers (they do not like it), then this is extremely bad news. Here is a core part of their workflow or reason for using your product and you've just made it worse!
Therefore, make these features better if you can, but do so with great caution. Perhaps test changes here in a small bucket of users first (say 1% of users or less).
Where to Experiment
The Feature Audit (where a green square below represents where a feature sits on our graph) can give us pointers for what may be great places to run experiments to improve our existing product:
If some/most customers are using a feature, then how can we get them all to use a feature? Particularly if those customers who do use it use it a lot (i.e. they love the feature), then there is a good chance that other customers would use it but perhaps they are not aware of this feature and how great it could be for them? Perhaps some messaging (an in-app message, an email etc) could explain why this feature has great value? This could be a quick experiment to run!
If you see many/all customers using the feature at least once but those customers don't use it a lot, then we know customers are aware of the feature - after all, they have used it! Although they know the feature exists, they didn't see the value of using it more often. Therefore, explaining the value of the feature and the related benefits of using it could be very effective and could make another ideal experiment
Summary
Doing a Feature Audit for all the main features of your existing product will:
Help you learn which features customers love
Help you identify which features to make customers more aware of and when to explain the benefits in greater depth
Give you ideas for lean experiments
Additional Resources
Intercom describing the Feature Audit
Aayush Jain tells a really nice story of applying the feature audit to housing.com