This is my opinion, and its just an opinion:
1. Use the correct charger. 5v, 1A.
2. Don't leave it unattended while charging, and a lipo bag may be wise
3. Don't use it immediately after charging. Let the batteries stabilize.
4. Don't use a leaky atty. If juice gets in it, its probably going to be ruined.
5. Take your atty off during charging and overnight.
6. Don't run it hard. I'm no longer subohming or running high wattages. I think the components aren't beefy enough, and it has no venting. I know it was marketed as a subohm device, but I don't think its up to the task. If you want to vape at 50W, I would buy a different mod. Luckily I have a lot of mods and was able to change things around.