Hand saws are available in many sizes and configurations; a good general purpose saw is 26″ long and has 8 teeth per inch. Crosscut saws (to cut across the grain) have teeth with a negative rake; ripping saws (to cut in the direction of the grain) have a zero rake.
How to make a cross cut
Cross cuts go against the grain, mark the cut with a square, guide the side of the blade with the knuckle of your thumb. Start the cut by pulling up on the handsaw two or three times, then push the saw forward at about a 45° angle, continue with full even strokes.
How to make a rip cut
While using hand saws, rip cuts go in the direction of the grain of the wood, mark a line to follow, start the same way as cross cutting, then continue with full strokes at about a 60° angle. If it is a long cut use a wedge to spread the wood apart.