The best firewood is always seasoned firewood. Seasoned firewood is wood that burns with less smoke and provides greater heat because there is no moisture in the wood. Seasoned firewood weighs less and is lighter in color because there is no moisture in the wood. It may also have cracks and look grayer in color.
The size of the logs you burn is also important. The wood you buy at the store or that has been delivered still needs to be split into smaller pieces, usually 2-3 inches in diameter.