Investing in real estate is all about making a profit. You either buy to rent or buy to sell at a profit. Doing either of these successfully will be helped if you learn how to value your investment. Value is not always about what a property is actually worth. Perceived value can be different to market value. This is what pushes prices up all the time. When the demand outstrips the supply the price goes up too. Never buy a property without examining the prices of other similar properties in the same area. This will prevent you making the costly mistake of paying too much.
Timing is important too. If the prices are starting to boom, you don't want to sell too early and miss out on a further rise, but neither do you want to leave it too late and miss out on a sale. Busts usually follow booms, so you don't want to miss out on the boom prices.
A time when prices have dropped is a great time to buy, but what if there is a boom on and you can't wait? Then you need to look for those properties that are on the market for a personal reason. Often those who are desperate to sell quickly for a personal reason will happily take a cut in price.