Try to correct your mistakes invisibly so nobody knows! Use corrector tape, such as Pritt Roller which comes in a plastic holder with refillable cartridges. Cover your error firmly and accurately, then with your middle finger tap the white mark about a dozen times to remove the brightness. Very often you can tone it down to match the shade of the newspaper.
The other method is to cut and paste a matching square from the edge of the newspaper, using Pritt Stick. For a complete word then cut out a measured strip and redraw the black bars using a fine liner and a straight edge.
These methods may sound fiddly but they only take a couple of minutes and might even win you a prize!