The best method for cleaning your chimney is scraping it with a wire chimney brush. The brush may seem expensive, but for people who burn a lot of wood and must clean their chimney more than once a year, a brush gives the best results. You can buy brushes from most retail outlets that sell wood-burning stoves or fireplace equipment. Brushes are available in different sizes depending upon the shape and size of your flue. Buy a brush designed to fit your flue.
Some brushes have a rope attached to one end to pull the brush up and down the chimney.
For this type of brush, attach a weight of some kind to the other end to pull the brush down the chimney. There are other techniques you can use with some degree of success, such as scraping the chimney with a burlap bag filled with straw or tire chains, chicken wire rolled into a ball, etc. The main disadvantages of these alternatives is that they are not able to provide enough abrasion to clean all the creosote out of the flue. Another cleaning technique that deserves careful consideration is system management. You can eliminate much of the creosote buildup with correct operation of the system.