Mostly from your own mistakes,through trial and error. Try out different strategies. Gather little snippets of info here and there.
i mean literally every youyube trader grom ross cameron to rayner teo to tim sykes say same thing I always assumed that they just have better data on their paid platforms. But maybe its just their experience and they can correctly guess who is moving the price based on what they see. I donno thats why i asked. You can just look at any of their videos of live trading
I am familiar with Ross, he definitely uses level2 and tape to make trading decisions. Give a specific example and I will give you specific answer.