Got it to turn on! (plugging into USB?)

[Akane]

I had a problem getting my i10 to turn on after turning it off and plugging it in to the USB to charge... but with a lot of prayer and persistance it turned back on a moment ago.

If I am listening to a song and decide it needs charging or that I want to go upload something else, is it safe to plug in the USB without turning it off/putting it to sleep? Is there an order to this sort of stuff, so I don't put myself in another hole like before?

Thanks so much ^_^