Sree, I don't make my trading decision based on such fundamental factors.
I refer to charts and take my trading decision.
Generally, for each industry, you will have a typical PE ratio .. there is no 1 single right or wrong number (during internet boom, companies with negative EPS were traded at crazy price. Maybe in recent past, you might find many real estate companies falling in that category).
So, if u find that on an average, energy companies are traded at PE multiple of 10, then u can use that as multiplier to get fair mkt price.
But again, if u use historic EPS, then u are making assumption that market conditions are going to remain same and company is going to earn in similar fashion.
And if you are using projected EPS, then again u are making assumption that people can predict future of market, economy and companies performance and decide that they will eary x EPS.
For me, both assumption are wrong so I don't go ahead with this fundamental approach for trading.
Let smart knowledgable analysts sitting at FII/brokerage house do this analysis. Finally they are going to come to market to buy stock.. and the stock price will tell me the truth. So I just watch the price and spend time there.
Happy Trading.