On slow combustion heaters ( when cold )' spray glass with plain water , wet soft cloth , dip wet cloth in grey ash from fire and rub gently on glass . repeat until totally clean . Never use scrapers or steel wool on glass.
Buy your wood from reputable dealers. green or unseasoned wood will smoke to excess and build up creosote in your chimney. seasoned wood is wood cut , split and dried for at least 2 years.