You may already be set to do this. If not, this will take a bit of planning on your part. Here are some tips to consider.
The moisture content of wood affects efficiency. Make sure to use properly seasoned firewood for optimal burning. If you are seasoning it yourself, make sure you have the proper wood harvesting knowledge, skill, and tools including a wood saw or chainsaw, gridiron, trivet, and spit. If not, you'll have to buy it pre-seasoned and ready to go.
Maintain a meaningful amount of firewood in storage so it will be there when you need it. Rotate through it and replace it when you can and use the FIFO method.
If you are planning on using firewood as one of your main fuel sources, here are tools you will want to have on hand: fireplace tool set (ash shovel, poker, etc.), fireplace bellows, ash bucket, hearth wood rack, firewood carrier, and outdoor wood rack.
Make sure to follow all safety guidelines when using a wood-burning fireplace, including having your chimney inspected and cleaned regularly.
Note: If you have a wood-burning or gas open fireplace with no glass enclosure, your fireplace is losing up to 75% of the generated heat to the chimney. If you would like to make your fireplace work more efficiently, especially if it will be one of your main sources of heat during a power outage, you may want to consider adding a fireplace insert. A fireplace insert increases the efficiency to 70 to 75% resulting in more available heat. You burn less fuel for better results.