Before searching for developers you should::

* define your app's scope

* create specifications

1) The biggest question is probably about total cost when outsourcing mobile app development. The development costs, the design, the mobile ad and the post launch support costs should be considered.

2) Lack of knowledge about the company reputation may be one of the biggest mistakes.

3) Also, your top priority should be the company innovation. It should be a company that can transform your idea into a reality innovatively.

4) They should be obviously a team of dedicated mobile app developers or your project can’t be sure to be handled from concept to launch.

5) Look at their customer service and account management level. If they lack in a dedicated support, you should consider.

6) Size matters, but not really. A good partner should have a team that can work on complex mobile projects -- but the team may only be 2 people and that's okay.

7) Look at the company’s portfolio with projects as yours before hiring them. If they have outstood in similar projects, then they are likely a good match.

8) See if they are also full-stack and expertise in different mobile technologies and platforms.

9) Make sure that custom mobile app development and specifications are provided that will match with your business needs.

10) It's important to get along with our mobile development team. Communicating more on the phone, in person, at dinner before signing the agreement. If it’s not comfortable to communicate, it's not going to work.