There are several common causes of glass breakages, anything from insufficient cleaning to overfueling or over-tightening the clips/screws can cause your glass to crack after installation.
Do not over fill your fire chamber with fuel that potentially could push against the door glass.
When re-fueling your stove make sure any logs can't fall into the stove glass.
Do not burn painted or treated wood as this gives off chemicals that can damage both your stove glass and flue liner.
Do not over tighten the clips that hold your stove glass in position.
Use the correct method of sealing outlined by your stove manufacturer and DO NOT use fire cement