The first and biggest mistake people make is to think that you can build a good trading system just on one indicator. There is no magic indicator, each indicator has his weakness. Combining indicators should help to overcome the individual weaknesses of each indicator.
Nowadays meteorologists are able to predict the weather for the next few days with high accuracy. They don't just watch at one "indication", they use the whole picture and analyze various things. Traders should do they same.
When researchers tried to find a vaccine against Covid, they tried to make combinations of different substances, they never were looking for just one substance that would miraculously defeat Covid. The same applies to trading.