One thing you can use when you are trading stocks or options is fundalmentals.
And I am not talking about PE which I believe is misleading.
1) Example #1, legal judgement or FDA ruling on a stock.
If you know the possible time frame, you could use a neutral trade like a straddle. Like all trades, they might lose you or make you money.
If the stock does not move up enough up or down, you will lose money on this trade.
So the opposite is to sell both the call and put if the option price is very expensive since you could actually make money on both sides of the trade.
2) Example # 2, hedge trade. A hedge fund is about to buy a company, so you want to buy the stock or options before they annouce.
You heard about this as a rumor or were sleeping with the CEO's wife.
The opposite, and an actual trade I am in right now, after hearing about the rumor that AMR was being bought out, I did some DD including checking the message board, and saw that one of the shorts discovered it was not real, so I went short on Friday. After the bell, that information came out that the buyout is false, so my goal is to ride the stock down.