Do not store a lithium battery with a very low charge for a long time
, the battery monitor will draw a small current, which might cause a 'deep discharge' which may cause damage to the battery.
Avoid cheap, knockoff chargers as they may cause excessive battery heating.
When buying lithium ion batteries, be aware that oxidation begins at the time of manufacture, not the time of first use. As such, older lithium batteries will have reduced capacity (about 20% per year stored at room temperature). If you buy a battery at a clearance sale price, expect that you will get less life out of the mobile phone.
Never dispose of old batteries in the trash. Batteries contain toxic metals, and electronic waste from batteries and other electronic components is becoming a major problem. Improper disposal of toxic batteries is illegal in many jurisdictions