Freelancer, agency, or in-house?
Freelancers suit small, well-defined jobs and tight budgets, but carry bus factor and coordination risk. An agency gives you a whole team and process, which fits most first apps. In-house makes sense once the app is core to the business and needs continuous work. Pick by stage, not by what's cheapest today.
Vet for seniority and ownership
Ask exactly who will work on your project and how senior they are — not who's in the sales call. Confirm in writing that you own the code and the app-store accounts from day one. A team comfortable talking about testing, releases and maintenance is usually the safer hire.
Questions that predict trouble
Ask for an app they've maintained for years, not just launched. Ask how they handle a missed estimate. Ask what's excluded from the quote. Vague answers, no named engineers, and a price far below the rest are the reliable red flags.