Love all, trust a few, do wrong to none.
By three methods we may learn wisdom: First, by reflection, which is noblest; Second, by imitation, which is easiest; and third by experience, which is the bitterest.
A successful person is one who can lay a firm foundation with the bricks that others throw at him or her. Confucius
“Most people get interested in stocks when everyone else is. The time to get interested is when no one else is. You can’t buy what is popular and do well.” Warren Buffett
"Know what you own, and know why you own it." - Peter Lynch
Do your homework before making a decision. And once you've made a decision, make sure to re-evaluate your portfolio on a timely basis. A wise holding today may not be a wise holding in the future.