The stove window can sometimes blacken up over time, you can use a wet cloth or paper towel to clean it when the glass is cool or for more stubborn residue the glass can be cleaned using stove glass cleaner, this is available from Lakeland or other retailers.
Burning kiln dried wood will help reduce the level of soot on the glass, as kiln dried wood provides a clean burn.
You should have your chimney or flue cleaned twice a year, the best time according to HETAS is just before the season starts and after your stove has not been used for a prolonged period after the season.
The best type of wood to burn in a wood burning stove is logs that have 20% moisture level or below. By choosing kiln dried logs this ensures the wood has a low moisture level as kiln drying is a very effective process. The benefit of using kiln dried wood is it releases less moisture and soot into your chimney, helping it to stay cleaner for longer, a well maintained chimney also helps to prevent a chimney fire.
You should empty the ash tray regularly, but how often depends on the level of use, it is best to refer to your wood burner instructions manual, some wood burner manufacturers suggest leaving some ash in the tray for when you light the next fire. According to HETAS you should make sure the ashes are cool and use safety gloves with a galvanised steel or metal ash bucket. Don’t put hot ashes in the wheelie bin.
When cleaning the exterior of your wood burning stove it’s best to refer to your instruction manual for advice. This article from Real Homes provides some comprehensive insight.