1. Look for problems that people face in their daily lives and find a solution for it through your app
I had thought about this several times, even if in general, not strictly concerning apps.
We do annoying and repetitive little things on a daily basis and we could invent objects that could solve them; it would be enough to start thinking, even observing ourselves, what we do during the day.
But then I didn't waste more than a minute on this ? (but it's a good idea, I think)
Excuse the vulgarity, but think about who invented the toilet paper roll! ?