^this.
Mr Buffet has said something to the effect of "The time to be fearful is when others are greedy. And the time to be greedy is when others are fearful."
I like to keep cash as a reasonable percentage of my total portfolio so that when buying opportunities present themselves I am able to act.
I have a mix of trading and investing in my accounts, with short, medium, and indefinite holding periods.
Do your research, do your best to educate yourself, and then you will be able to form you own opinions and disregard the talking heads and tabloidesque news articles on hot stocks or doom and gloom.
However be weary of anyone who tells you they completely understand the market or how it thinks. The same can be said for women...