Honestly I wish i knew. I find the battery really gets substantially worse after 12-18 months, and eventually I'm living with it plugged in to avoid getting caught with it low when I'm out.

Recently I dropped my phone (while in a case) and now there's a black spot on the screen.

Stuff like this. I live a life between a lot of DIY work and software dev, so I'm physically probably rougher on it than most, but also a heavy user of the technology too.