Lots of reading, disciplined strategy

It's hard to boast of much success in the current situation, but what worked for me is:
1. Always read as much as you can. Read broadly, read deeply, and associate what you read into current affairs, the companies or sectors you plan to invest in, the people they serve or sell to.
2. Decide on a plan/strategy to invest and stick to it. eg hold x% cash in good times and invest y% when markets dip, take profit at 20%, whatever.