Get specific about the problem you are solving and who you are serving.  Identify your value propositions and workflows.

Identify and refine your brand identity.  Use it to inform your visual aesthetics.  Build designs that communicate your values.

Select the features you need to launch.  Build the app, website, marketing tools, etc.  Get feedback early and often.

Bring on your first users.  Start your marketing.  Understand user acquisition.  Identify and fix common pain points.

Revisit your assumptions.  Figure out what's working and remove what isn't.  Measure and improve your messaging.

Release updates to keep up with changing platforms.  Improve the user experience and fix bugs.  Keep your design fresh.