The Federal Trade Commission (FTC) has issued new guidance on how mobile-application developers can avoid running afoul of truth-in-advertising and privacy laws. As the FTC notes in its guide, Marketing Your Mobile App: Getting It Right from the Start, advertising, privacy, and consumer protection laws apply to companies of all sizes. And as recent FTC enforcement actions have shown, the penalties for noncompliance can be devastating.

The short FTC guide provides several obvious but often-overlooked pieces of advice. First off, tell the truth about what your application can do. A little puffery is okay. Sprinkle on the generous adjectives. But if you start making objective claims–especially health, safety, and performance claims–you had better have solid proof. And if you have to disclose some product limitation or untested claim, disclose clearly and conspicuously. Burying a disclosure in 20 pages of text isn’t going to cut it.

On the privacy front, the FTC advises building in privacy considerations from the start, and being clear with your users about what data you collect and how you use it. Don’t collect sensitive information without consent and a way to opt out. Carefully guard the data that you do collect. Get parental consent before collecting data from children under 13. And above all else, do what you say you will do. Tell the truth.

Too often in the win-at-all-costs world of startups, companies cut corners and break the rules to attract early customers and generate buzz. Just look at Airbnb or Spokeo. This FTC guide is a reminder that no matter how small your startup, no matter how desperate your need for growth, you have an obligation to consumers. If you ignore your obligation, it may be enforced to devastating effect.