On a given roulette, the house wins just over half of the time. He's too busy in the back room counting the 1 or 2 cents on every single dollar that passes through each station and piling up the pennies by the millions. Be quick to sell the stocks that don't work out and slow to take profits on the winners. Too many clients I know lock in small gains and take huge losses due to some quirk in their primal greed response. Act on facts, not emotions.
Parents always think that their kids are the cutest in the world, but an ugly baby is still ugly.
Don't get blinded by your own prejudices into making a prince out of the frog next door. Realize that just because you feel a certain way about a stock, industry, product or service, doesn't mean that anyone else does. Then, if you see some areas to change for better performance, do it, but stay with the system and don't second-guess yourself. However, as a beginning investor, forget about trying to take advantage of those gyrations. Face the facts that you'll probably be the last to know about any information that drives prices in the short run, and focus on hitting consistent singles over months and years instead of trying to blast a home run once a decade.