@nitesong The main things about battery safety, buy from a reputable vendor, RTDvapor is one of my favorites, others will chime in. If you are using them in a multiple battery mod, two or more batteries, label them in a manner that you will know they all go together. Discharge them as a set, charge them as a set and always keep them as a set. Don't grab one one day and use it in something else, don't mix and match them, they are paired or "married" for life now. This helps eliminate the problems of having one battery that has a higher capacity than the other one in use. What happens then is the higher battery works harder trying to make up for the lesser charged on and goes thermal. That's not good.
How and where should the married batteries be labeled?