How to charge an iPhone?

I know this sounds crazy.😂 The iPhone 5s that I have and am currently about to get rid of got messed up due to me charging it all crazy, I'd wait until my phone was almost dead before I charged it and then would end up unplugging it before it was completely charged. It ended up messing the battery up and my phone would get so hot that it would literally burn my hand to even hold it. I got a new iPhone 6 and just don't want to mess it up like I did the 5s so I wanted to make sure I did everything right by this phone and take extra care of it.

*Also I've had the 5s a year and it didn't start burning up like that until a few months ago, then it would cause my phone to like freeze up for a few seconds while I was using it.