So you must have a vision. What is it that you trying to build?
Then the step after that would be build something you can get in front of users and get feedback.
That's your first 3-month strategy
Second 3-month strategy would be to build on that. Build the prototype and show it to more users.
After you've figured out the product a little better. You can start doing longer term planning. 6-month plan would include building a product further, getting feedback, getting first beta users, building a marketing engine.
You should always plan if not for anything else but to keep you on track. Even if it's the wrong direction, with a plan you'll know sooner than if you just keep wondering around with purpose.