Mobile apps are now mainstream with an estimated 352.9 billion apps expected to be downloaded in 2021. Nevertheless, as many as 25% of users open an app once and never return. So how does a mobile app become useful, relevant, and valued so it delights and retains users?

A mobile product’s UI plays a significant role in its success or failure and the loyalty of its users—hiring a top-rate freelance mobile UI designer is a great investment and can lead to an exponential increase in revenue, exposure, and credibility.

Look for someone who is a creative thinker, a good communicator, easy to work with and committed to your success. The designer you choose should be able to show that they can work to your creative brief and design with your objectives in mind.

In order feel secure about talking to candidates and being able to ask them intelligent questions, it’s a good idea to become familiar with some basic UI Design concepts. (See article “The Ultimate Guide to UI Design” at the bottom of that page.)

1. Ask to see a freelance mobile UI designer’s portfolio and make sure it suits your needs:
   • Make sure their past experience and portfolio includes a selection of mobile UI designs—also ask about what inspired their choices. It may give you insight into their creative process.
   • Make sure they have a genuine understanding of the design differences between “native” mobile apps and responsive websites.
   • Make sure they know the difference between a Progressive Web Application, which is an app within a mobile web browser, displayed as a website, and a native mobile app.
   • If your app has special features that require access to the mobile’s native hardware such as the camera, microphone, accelerometer, GPS, fingerprint sensor, etc., make sure the designers you are considering have experience with these components.
   • A great mobile UI designer understands the importance of usability as well as some UX concepts such as designing for smooth interaction.
   • A great mobile UI designer knows it’s not just about aesthetics.
2. Craft a well-thought-out mobile UI designer job description—be specific about what you are looking for and clear with your goals and expectations. Include:
   • The problem you’re trying to solve.
   • The skill level you’re looking for.
   • The intended audience.
   • The technical specifications, project constraints, deliverables and timeline.
3. Define your project scope with a creative brief—a document that provides contextual information about the project and the candidate’s potential role:
   • Information about your business or industry.
   • A summary of your project.
   • Technical specifications of the project.
   • Your target audience and any research into their preferences.
   • Sample user storyboards, user journeys and user stories (if available).
   • An overview of what the competition is doing.
   • Relevant details about your brand, including tone, style, and design guidelines.
   • A project timeline, including any key milestones/deliverables and testing timelines.
   • Your budget.
   • Other designers or developers they’ll be working with on the project.
4. Word of mouth works—get recommendations** and ask for references** from previous clients.
5. Stay away from the crowdsourcing or competition sites—experienced professionals typically don’t use them.
6. Search curated design networks (word of warning here: these are often experimental sites, especially Dribble, that show a ‘concept’ design of a single screen for an imaginary app, not a real world, functional product that has been released). They are:
   • Behance
   • Dribbble
   • Coroflot
   • Cargo
   • Carbonmade
7. Ask the right questions: Try not to ask questions that are too vague or too specific—blasting candidates with overly complex questions will confuse the issue and make it more difficult to get a clear idea of their ability. If you feel unsure of what to ask, consider including an interviewer who has a deep understanding of UI in the process who can ask the tough questions. Get to know them a bit—ask a couple of questions like:
   • Has your interest been piqued by any UI designs lately? What are they?
   • Which product designs have really inspired you lately? What are they?
8. Great designers can really get into the user’s head. To them, it’s all about the user experience. They can walk in someone else’s shoes and develop a deep understanding of a person’s wants and needs. So hire for empathy and openness—work processes into the interview that give the candidate an opportunity to show these attributes:
   • How do they incorporate user feedback into their work?
   • Ask them a tough question about one of their designs, or tell them you don’t understand something and give them a chance to explain it to you.
   • Give candidates a chance to show empathy for their users too. Key questions:
     • Describe the users of this (portfolio piece) to me.
     • What do they care about?
     • What are their pains and goals?
9. Try to find mobile UI designers who understand the importance of user research. In a nutshell, user research is “the process of understanding the impact of design on an audience” (Mike Kuniavsky), and if you are serious about creating a great product that satisfies your users’ goals and delivers an exceptional user experience, then investing in user research is a crucial. A couple of questions to ask candidates could be:
   • What do you need to know about the user before starting a project?
   • Do you carry out user research before you start designing? If yes, how?
10. Until you get user feedback, you won’t really know how people would use your product in the real world, or what they think about it. User (or usability) testing gives design and development teams an opportunity to identify issues before they are coded, thereby saving time and money. Ask candidates:
    • Have you done any mobile user testing as part of your design process? If not, why not?
    • If yes—how did you test your design on users, how did that go, and in what ways did it alter or impact the design?

Single mobile screen designs in a portfolio can be misleading—a beautiful design also needs to be functional, and if you’re not careful, you may find yourself with an interface that looks amazing but is completely useless.

If you still feel unsure about your understanding or experience of UI design after spending time to learn a bit about what it entails, you should either involve a trusted, experienced UI designer in your interviewing process or you use a service, like Toptal, that prescreens candidates for you.

Mobile designers always have to be on top of their game and keep track of the latest design trends and upcoming hardware. In this fast-paced and highly competitive niche, expert designers have no choice but to pick up new skills and adopt the latest technologies on the fly.

At Toptal, you’ll connect with top hand-picked freelance mobile designers from our network, trusted by top companies on their most mission critical mobile design projects.