In all wagering activities you should try to buck the market. If the stock market is high, that is the time to sell. You may miss the final flourish before shares plummet, but you cannot time things perfectly.
When betting on a horse, you should be looking for a bet which is good value for what you perceive to be the horse’s chances.
When playing poker, the playing may be slow and cautious. You should play loosely and aggressively. But be careful, the last thing you want is for your hand always to be up against the lone best hand at the table. If the game is vigorous and loose, you should play more defensively and tighter.