Investing properly means buying low whenever possible. Damaged stocks are ideal for this, but you have to avoid damaged companies. Damaged stocks will recover, and can end up earning you double the money you invested. But a damaged company may never come back, making for a meaningless investment on your part.
You always need to diversify your portfolio. Don't just trade stocks, you need to invest in things like commodities as well.
You need to manage your expectations, and really focus on making intelligent decisions that are not motivated by your emotions.