Write unbalanced ionic equations for the two half-reactions.
(Look at oxidation numbers in the "skeleton equation")

Balance atoms other than H and O.

Balance O with H2O.

Balance H with H+.

Balance charge with appropriate number of electrons.

If in acidic solution, then skip to step 7. If in basic solution, then add equal number of OH- to both sides to cancel all of the H+.

Rewrite the balanced half reactions.

Multiply balanced half-reactions by appropriate coefficients so that the number of electrons are equal.

Add the half-reactions together.

Cancel species that appear on both sides to get the balanced Net Ionic Equation.

If necessary, add spectator ions to get the balanced molecular equation.