If you have a fireplace or a wood burning stove, make sure that you clean your chimney at least once a year. Burning wood in a fireplace or stove leads to creosote build-up in your chimney. If you get too much creosote in your chimney, it can catch fire and the result of this is often a lost house due to fire.

Getting your chimney swept is fairly expensive (it tends to run about $150 where I live), but it is well worth the cost when you consider what can happen if you do not clean you chimney.

An even better solution is to clean it yourself. If you have a straight chimney and easy/safe access to your roof, this is surprisingly easy to do. You can buy a special chimney cleaning brush and the rods that they go on at most places that sell wood burning stoves. The cost of these is pretty cheap (usually less than $50) and they pay for themselves immediately when you consider the cost of getting this done professionally.

When you are cleaning your chimney yourself, make sure your flue is open. Also make sure that your stove/fireplace doors are shut. If you can not completely seal the doors of your fireplace, tape plastic around the opening to seal in all of the debris that will come down when you run the brush down your chimney. If you don't do this, you'll end up with creosote throughout your house.

Once you take care of that, you just get on the roof and run the brush up and down the chimney a couple times until the pipe/chimney looks clean. What for the dust to settle inside and then clean up all of the creosote that is now in you fireplace or wood burning stove. All told, this take less than an hour to do. Given that not doing this can result in your house burning down, it's well worth the effort.