Crash Course Points:
1. Use a good balance charger. One where you can set the charging Amps and where you can see each cell's voltage. Most will also detect if the battery is ok to charge before it charges it.
2. Get a little dongle things that checks the voltage off of the balancing tap. Most will display the voltage of each cell and the total voltage of the pack. ALWAYS check the voltage of the cells before you charge....if any of the cells are below 3.0V you should either not use that pack (I'd try to balance charge it anyways...but be watching closely).
3. NEVER charge at more than "1C" of the pack. If your pack is 1100mAh...then don't charge at more than 1.1A (1A would be safer). If your pack is 2000mAh...then 2A would be ok. Charging at less will do no harm, just take longer (be aware of your charger settings...some turn off automatically after a set amount of time).
4. ALWAYS balance charge a LiPo. Use the balance taps of the pack...use the balance ports of the charger.
5. You should never have to discharge your LiPo's. If they're low and you're going to pack them away for a while...then charge them up and pack them away.
6. If your pack is torn/scratched up/twisted/mangled/bulging/hot....don't use it. Don't charge it...don't discharge it...don't do anything with it. Dispose of it responsibly.
1. Always start with a fully charged up battery
2. If it's a new pack...and/or if you're new to LiPo's...use the balance tap display thingy to check the voltage of the pack periodically (like when reloading or between games) to get a sense of it's behaviour in your setup.
Make note of how much you shot...how did the gun sound/feel...etc. Every setup is a little different...and every battery might be different from another one of the same type/rating.
3. When ANY one cell in the pack approaches 3.1V (really it's 3.0 but leave a margin of error)...stop using the pack. You'll have probably noticed that the ROF has dropped or the power is running out by the way your AEG behaves....but the drop off is pretty quick in a LiPo so it's not as apparant as other battery types.
When ANY one cell is driven down below 3.0V, that cell is "dead" (generalization...but safe way to think of it).
The danger comes when you pair a dead cell with a dumb charger and have a dummy press the go-button. If the dummy and the dumb charger don't detect that the cell is dead and tries to force feed power into the pack they might over charge the other cells (past the 4.2V limit / cell). The cells won't like that and they'll throw a fit (i.e. boil the chemicals and try to burst). The packaging of the cells is supposed to contain that...but use caution.
When using a battery...they're meant to discharge at a given spec. If your pair up a "little" battery with a really power hungry setup it'll try to draw more power faster than the pack is rated for. When any battery discharges it produces heat from the chemical reaction in the cells. If it's too hot it'll boil the chemicals...and the cells will throw a fit. (opposite reason from bad charging...but same effect). So if you're using a battery and it gets really hot (like too hot to touch)...STOP using it. If it's badly bulged/puffed/ballooned....it's no good anymore and you should dispose of that pack.
That's the coles notes I'd have for using LiPo's.