The strategy plan's probably the hardest part and the one we spend the less time doing. Yet it's crucial to spend quality time reflecting on what will really matter in the long run.
It can be very simple as long as it clarifies how you're going to create value in your project. Make sure all your team members need to agree with it. And work towards it!
To put it plain: it has to work. Otherwise ditch it and pivot, i.e. keep what you've learnt from the past and change your value proposition. It's much harder than it seems but it'll save you from great trouble.