It's hard to say without some more information: What kind of app are you making? What is your vision for it? What do you see as the most important goals? Some commonly used goals for mobile apps include number of active users (daily or monthly, DAU/MAU), retention (7 or 30 days), revenue, conversion (from free user to paid, mostly for "freemium" business models). Without knowing more about what industry you're in, your objectives, or your vision, it's hard to say. If you don't have a goal set right now, I would definitely suggest picking one before continuing and let it guide you towards building a great app. Good luck!