FWIW here's the 'battery rules' I follow:
- Fly with a timer so that the battery after removal from heli tests at 3.7V per cell minimum.
- Minimise the time that the battery spends fully charged, so only charge on the day of flying.
- Balance charge at 3C max (more often i use 2C charge)*
- If I charge but dont use a battery I either discharge to storage or for short duration storage I seal it in a bag and put in fridge fully charged.
- Storage voltage is anything between 3.7 and 3.9V (so as it comes off the heli is usually fine)
- Avoid leaving battery in hot places especially when fully charged.
*Note that your charger is limited to 100W of charge power so the most you can do on that battery is a 1.5C charge, so dont worry about charging too fast.