But before those good traders reached that positivity rate in trading, they experience several losses on the way first.

You need to pick some coins based on what you think is worth it. That includes a test run of your selected coins and accepts that a loss is possible on the way.

As long as you continue doing that, you will now be used to it, and picking good coins should not be a difficult task for you. Anyways just want to remind you that even professional traders still lose today so don't think that a good trader always has a good positivity trades.