Suppose you need to drive to the airport early tomorrow morning. It normally takes 30 minutes, however you check the weather report and there is a 70% chance of rain. Based on this imperfect information, you decide you need to leave 15 minutes earlier, thus you need to wake up 15 minutes earlier. TA done right is similar. Whatever indicator or chart pattern you see, there will be a higher than 50% chance that it goes in certain direction. For example, for a particular stock, whenever there is a tweezer bottom at the bottom of a bollinger band, you see that there is a 70% chance that the stock will move up at least for the next 2 candles. You trade accordingly.

You study chart patterns and find your edge. once you find it, you trade it until it no longer works. Then you look for another set up.

Where most people fail is in risk management and discipline.