I am Lead Android and back end developer in a logistic company. I am an Engineer by profession and have designed architecture, UI and databases of many android apps. I am also a well known competitive programmer having 99.9 Percentile (top 100) on Hackerearth. That said, I have delivered projects with 100 percent completion rate, I bid on only those projects which I am confident of completing successfully.
My work approach -
1) Gathering requirement and making wireframes (good if provided by employer)
2) Then I pass wireframes to my freelance designer colleague for designing (employer can provide their own designs)
3) I start with UI and fill it with dummy data. Filling it with dummy data gives more clarity on APIs.
4) I design backend database and APIs
5) I Integrate APIs in android app
6) Testing
7) Release