Swagatron, 3 chainz, and big baklava
According to Google research, 26% of all installed apps are used no more than once. The main reason for this is poor UI. To engage users into your interface, you should follow the most recent design trends.
In just a few words:
I recommend creating Flows first if you have the existing solution. If you are starting a fresh project, try to build user Journey Map that will be later validated by User Flows.
Every decision in your design needs to have purpose. You should be able to go back and explain why every pixel is the way it is.