You should save cash when the gold’s prices are high and buy it when the prices drop. Moreover, you need to know the lowest and highest price of gold over the last 20 years. Based on that, make the purchase when it is around 20% of the lowest price and sell it before it reaches 20% of the price.

However, the type of gold differs, not to mention the differences in selling price and purchase price, especially the high-quality and so on.