0. Sometimes it takes MORE time and effort if you outsource it. It might take as long to find candidates and describe your requirements as if you build it yourself. And you might choose an incompetent freelancer/company and have to restart the search again. I feel it's only worth the effort to find a good developer if you plan to work with him for more than just several months.
1. Try to get a referral. It's way easier to find a reliable developer this way.
2. Avoid popular freelance marketplaces like Upwork. The competition tends to drive away non-desperate developers (like me).
3. Be as specific as possible in describing what you want to build, provide a mockup if possible. Especially if you won't meet the developer IRL.
4. Find someone who speaks English and communicates proactively, who reports progresses and delays without you asking. It'll drive you nuts if you don't know if a deadline will be met and your developer won't reply to your email.
Finally, you can send me an email if you're interested in having my company build your MVP for you.