One indicator cannot gives you the exact result. You can use multiple indicators to verify the trend. And if all indicators sows the same result. It means you can choose this trend to open a trade. If all indicators that the market is in oversold position then take a long position and if the indicators says the market is in over bought condition then open a short position.
That would seem like a good option but it is not, the reason for this is that by the time all the indicators you have selected indicate that a particular trend is present, most if not all of the trend is already over and you have no chance of taking advantage of it anymore, so this idea that our trading risk can be diminished in this way is not wrong, but by decreasing the risk you are also decreasing the size of your wins, so this idea is too conservative and unprofitable for my tastes.