One solution that I have found to remove creosote build-up is to throw all of your potato peels and available acorns directly into the fire. The potato peels can be collected and added whenever you have them.
Soot and dirt can stain the bricks on a fireplace, but there are ways to get them surprisingly clean. This is a page about cleaning fireplace bricks.
If you have a wood-burning fireplace you need to have the chimney cleaned and inspected yearly. Also only burn fully dried hard woods to produce the most heat output.
It is getting to be that time of year and in some places already cold enough for that evening fire. So before this starts many people have their fireplaces checked to make sure the chimney is clear of all debris, animals, and built up soot.
Simple, no cost. Take damp newspaper and dip in cold wood ashes. Rub on glass until creosote and film come off. Repeat as needed; finish with window cleaner. Works better than anything I buy.