I am currently reading Invest Like a Shark by James DePorre. For those who don't know, Deporre, otherwise know as Rev Shark, lost his hearing, job and wife before starting to trade with a $30,000 stake and turning it into millions.
Thus far there isn't much that I already don't know. However, from time to time it's worthwhile to review what you know to get the mind focused on what's important. For example, DePorre likens successful small investors to sharks, who patiently wait for an opportune time before striking aggressively. I like the analogy and I am already waiting for better setups.