1. Separate the two half-rxns
2. Balance all non hydrogen and oxygen atoms
3. Balance H and O (I usually do O first)
-> in acidic solution balance O with H2O and H with H+
-> in basic solution balane O with OH- and H with H2O
4. Balance the overall charges of each rxn by adding electrons (e-) to the side with the more positive charge. If the moles of electrons are unequal you should make them equal by multiplying one of both. In the end you should have equal moles of electrons on different sides which cancel when you add them together.
5. Add the two half-rxns, and make sure everything balances out (ie if you have 3H2O -> 1H2O then you should remove one H2O from the right and it will be 2H2O on the left.