Visual Design Resources

The best product designers I have met who has the ability to make an app design standout and let it have it own identity had one thing in common, the quality and diversity of references they had and their ability to remix those and make a new thing. I think if you have seen and observed a lot of good designs and interaction you slowly and steadily build a strong sense of visual direction, this ultimately helps you reach the goal you're looking for.

Designing Interface is a resourceful book from Wiley and Practice by Recreating Things, YouTube :).

Or if you wanted to learn all the nuances and do and don’t try adam’s practical UI.