Follow these steps:

Define your goals and objectives for the app.

Identify your target audience and understand their needs and preferences.

Conduct market research to analyze competition and identify gaps in the market.

Develop a wireframe or prototype to visualize the app's user interface and user experience.

Create a detailed project scope, including features, functionality, and timeline.

Assign roles and responsibilities and establish communication channels.

Develop a project schedule that includes milestones and deadlines.

Create a budget that includes development costs, marketing expenses, and ongoing maintenance.

Define quality assurance and testing procedures to ensure the app functions as expected.

Monitor and evaluate project progress regularly, and adjust the plan as needed.