It is the time of the year to be using your fireplace, before you start using it you will want to be sure that your fireplace is clean. Ideally, you should clean your fireplace in the summer when you won't be using it for some time, but if it has not been cleaned, then there is a risk of having creosote or soot cause a fire.
Now you will want to be sure that all the ash has cooled before you go about cleaning your fireplace.
To remove the ashes you can use fireplace tools such as shovels, brooms, ash rakes, etc.
Once the ashes have been removed you will need to take out grates, andirons, fire-backs, etc. I recommend taking these to the yard to clean with a wire brush, then you can use a specialized polish on them to restore them to look practically new. Now is also a good time to clean your fireplace accessories.
You will want to use a wire brush to remove any build up of creosote and tare on the damper and lower part of the chimney. Shovel or vacuum this debris out of the fire box.
To clean the firebox you can use solvents created for cleaning fireplaces, you can also use washing soda, vinegar, or TSP with warm water. Use a stiff bristled brush on the inside of the firebox once your cleaning solvent of choice has had time to soak.
If using hot water & vinegar or hot water & washing soda you will want to scrub the liquid into the firebox and let it soak for about 20 minutes or so. Come back and scrub your firebox and fireplace with a generous application of this cleaning liquid.
Once your fireplace is clean you will want to rinse it off with warm water. Let your firebox air out and dry. Close your damper to prevent the fireplace from sucking air out of your home. But be sure to open it before starting a fire.
You will probably want to go ahead and clean your chimney at this time, also suggested reading: Chimney & Fireplace Tips