Instructions
Purchase an Xbox Live 3-month Gold card at full price. These cards carry enough points to sustain an Xbox Live Gold membership for three consecutive months, before they will need to be renewed.
Purchase an Xbox Live 12-month Gold card for around two and one-half times the cost of the three-month card (as of 2010)--a much better deal. These cards carry enough points to sustain an Xbox Live Gold membership for 12 consecutive months, before they will need to be renewed.
Purchase an Xbox Live 12-month plus 1 bonus month Gold card. By far the best deal, these cards are typically only available during certain periods of the year. They carry enough points to sustain an Xbox Live Gold membership for 12 consecutive months, plus an additional full bonus month.