As a leader, you try to develop a strategy for your team. The last days I have struggled a bit with this topic. So here are my thoughts based on severals conversations about it.

If you try to develop a strategy you need to have several things clear. One of the major thinks that need to be clear is the purpose and the vision. (There are even more things to take into consideration like: what problem should be fixed, is it measurable...)

Purpose Pyramid

Pyramid with Purpose - Vision - Strategy - Tactic

The purpose is the fundamental thing to build a strategy or even a tactic. Based on purpose you can develop one or more visions for your team/company/product. I think there shouldn't be too many visions - one could be totally fine.
For each vision, you can have several strategies which are getting more and more precise. At last, you develop one or more tactics to archive the strategy goal.

So basically you develop guidance from a very abstract level (purpose) to a concert action (tactic).

One is based on another

If you try to develop a tactic you need to have a clear strategy.
If you like to create a strategy, you need to have a clear vision.
If you need to think about a new vision, you need a purpose.

The purpose should be the only thing which is consistent as long as you do the same business than before. Then the purpose describes why are you here and why are you doing what you do.

For Example, the purpose of Google is:

Google’s mission is to organize the world’s information and make it universally accessible and useful. (https://www.google.com/about/company/)