Building an app is a big investment! Firstly you need to consider the return on investment and whether or not an app is right for your business. Next up, you need to ensure there is a demand for your app. Lay out the flow of how it will work and ensure that design comes first. Now comes the important part: hiring a designer/developer. Engage an app development agency, preferably with experience in your industry. They will help you to design the app and then build a prototype for testing before you launch to your audience. It is important to integrate analytics, so you can measure success of app. Remember that you need to introduce new features on your app based on feedback and user flow. Many companies use the strategy of launching a minimum viable product and then adding features in subsequent versions.