Jesse Livermore actually goes into pretty good detail of what he did. Keep in mind this was during a different era and trading was much different then. The guy would have a ticker tape machine in his office and he would simply watch the prints. He could tell if someone on the floor was accumulating or distributing stock. He would stay in the stock for hours, days or weeks as long as he saw buyers accumulating stock. As soon as he saw distribution, he would get out. Now this was much easier to do then this way because there was very little volume compared to today so these single prints would stand out a lot more. Plus when a large buyer or seller came in, they were much more easily spotted. But the same principles apply today. It's just today we have futures and options and options on futures and ETF's and day traders and everything else that create noise around what's really going on. It means you have to focus that much harder then you needed to then. Between one of his favorite tricks was he would send out market orders for small amounts to see the exact price he got filled out to spot the real buyer or seller. Amazing, over 100 years and that technique still works wonders.