Most sewers will wash and dry the fabric at least once and Flamingo buckle up buttercup you just flipped my witch shirt. Nothing worse than sewing a nice shirt and then discovering that shrinkage has made the shirt too small. It is also advisable to wash the fabric prior to cutting to remove all of the manufacturing chemicals which are used to make the fibers move through the machines easier. When I make a shirt I usually get 2.5 yards for a size medium using 48″ fabric. An extra half yard for a larger person. But do experiment with fabric layout. You will find that some pattern companies just use a generic layout and not necessarily a layout that will account for using the fabric efficiently.