Assign oxidation numbers based on common rules
Free elements have oxidation number 0
Monatomic ions have oxidation number equal to their charge
Group 1 metals are usually +1
Group 2 metals are usually +2
Fluorine is always -1
Oxygen is usually -2
Hydrogen is usually +1
Sum of oxidation numbers in a neutral compound is 0
Sum of oxidation numbers in a polyatomic ion equals the ion charge
Use known oxidation numbers to solve for unknowns
Check for exceptions such as peroxides, hydrides, and compounds with fluorine
Verify the result by making the total charge balance correctly