A hand plane is only as good as the hand that wields it. The first act in wielding it properly is to tune, sharpen, flatten and true it. While machines can often accomplish a job even when they are not quite sharp or tuned, a hand tool has more exacting requirements. Because your muscles are the only power behind it, you need to make sure that it's as sharp and accurate as possible.
Remove the iron from the hand plane. The iron is the sharp, flat piece of metal that sticks down through the bottom of the plane. Remove the wooden wedge and take out the iron, or loosen the bolt on the face of the iron, depending on the type of plane you have.
Tape a piece of emery paper securely to a piece of glass. Set the glass on a sturdy bench.
Run the plane back and forth over the emery paper for five minutes. Inspect the sole of the plane. It should be shiny and flat. Use butcher's wax to help it glide more smoothly and protect it from rust.
Hold a combination square against the side of the plane iron with the straight edge parallel to the sharpened edge. Draw a line across the end of the plane iron so that the line is perpendicular to the side of the iron.
Square the end of the plane iron using a grinding wheel. Hold the iron lightly against the wheel. Grind the edge until it matches the marker line that you drew.
Hone the edge of the iron. Use a succession of two or three progressively finer sharpening stones.
Place the iron back into the plane. Replace the wooden wedge or reattach the bolt, including the "frog," which is used to adjust the plane iron.
Hold the plane upside down. Sight down the length of its sole. You will see the edge of the plane iron where it protrudes below the face of the plane's sole. Adjust it so that it protrudes evenly, just a tiny fraction of an inch. Tighten it so it doesn't move.
Move the iron farther up into the plane if it catches when you plane wood. If the sharpened edge fails to plane any wood, move it farther down.