DO NOT clean while it is hot: The hotter the glass is the easier to clean, but you should always wait until your fireplace glass is cool enough to touch before cleaning wood burner glass. If not, you risk causing personal injury or shattering the glass.
DO NOT spray hot glass with water: Spraying your hot glass with water can cause thermal shock, which can crack or shatter the glass.
DO NOT use razor blades or steel wool: Abrasive cleaners like razor blades, steel wool, or even sandpaper will take the soot off of your fireplace glass almost immediately, but it comes at a price. These methods of cleaning fireplace glass can leave scratches that cause the glass to become dirty more rapidly by accumulating soot the crevasses, and the next time it can lead to glass failure in the fireplace.
DO NOT use oven cleaner on the glass. Oven cleaner will clean off the surface of the glass, however, it also removes the surface of the glass. The oven cleaner eats away at the glass surface, opening the pores and over time lets the dirt into the glass pours making it impossible to clean the glass. Using oven cleaner on the glass does more harm than good.