Things to be careful about when developing a mobile app

When developing a mobile app you need to focus on many things so that your mobile app can be something that people can turn to in their time of need. It should be a means for users to solve their problems because if your mobile app doesn’t solve your user’s problems then they probably won’t download it. So I thought I’ll make something like Uber and now I was concerned about the cost to make app like Uber. I wanted it to be affordable for me and since I didn’t had to spend any money on research therefore I got the mobile app developed in a very affordable cost. What other things should one be careful about other than cost when developing a mobile app?