Read up,do research,nothing to be scared off,lots of horror stories,but thats like me telling you not to drive a car as people crash into you(in fact far more chance of that than an li-ion exploding)
Point being,research,decent branded cells and charger,dont leave unattended no matter what precautions as with anything,nothing can be relied on(if makes sense)
Example- leaving on over night whilst asleep,leaving on charge and go out,just dont leave alone for hours..............simple as that
Also voltmeters are cheap,check cells,also will be able to check charger after ...........charging. Should be around 4.2v after charge........
Lots of info on here,dont be put off............i am not!!!! no need to study for days,just the basics