First of all, let's watch and bust some well-known myths about charging and reveal some facts:
Fully charge + fully discharge: Is it right?
Nop. Well, it's not any bad if you do this, but this method is completely unnecessary in newer phones using Lithium batteries. This method was used because of calibration of old batteries with memory effect, such as NiMH or NiCd. If you own a newer phone, you don't have to fully charge and discharge your phone.
However, it's known that newer types of batteries (LiOn/LiPo) don't like extremes - which means 0% discharge and 100% charge. If it's possible, don't let your phone to completely discharge and plug out your charge just before the percentage hits 100%.
Don't keep your phone discharged for a long time
This is bad. If you keep your phone with completely discharged battery for a week or two, your battery will be totaly damaged and you can go and buy a new one. If you know you won't use your phone for a long time, charge it up to 50%. (Again, don't charge it completely.)
Keeping your phone charging overnight
You can wave goodbye to your battery.
Check the original post:
Is it necessary to use the original charger?
It is. You may use a more powerful charger which will charge up your battery much faster, but this also damages your battery. If you have enough time to charge your battery with the original charger, use the original one.
Enemy #1 - High temperature
Lithium batteries literally hate high temperatures. For instance, if you leave your phone in 40C (104F) for one year, the battery will lose 35% of its capacity.
One more tip - It's not a bad idea to turn off your phone while charging.