For instance, it is possible to construct an option strategy in the futures markets that is affordable without sacrificing the odds of success...but with the convenience comes theoretically unlimited risk. This is easier than it sounds, similar to the way you would borrow money to pay for a house or a car, you can borrow money from the exchange to pay for long commodity option trades. There are an unlimited number of combinations of self-financed trades but they are typically going to involve more short options than long options, or at least as much premium collected on the sold options than that paid for the longs. In essence, the money brought in through the sale of the short options goes to pay for the futures options that are purchased. The result is a relatively close-to-the-money option with little out of pocket expense but theoretically unlimited risk beyond the strike price of the naked short options.
Puts are more or less the mirror image of calls. The put buyer expects the price to go down. Therefore, he pays a premium in the hope that the futures price will drop. If it does, he has two choices: (1) He can close out his long put position at a profit since it will be more valuable; or (2) he can exercise and obtain a profitable short position in the futures contract since the strike price will be higher than the prevailing futures price.
Remember, a stock option contract is the option to buy 100 shares; that’s why you must multiply the contract by 100 to get the total price. The strike price of INR 300 means that the stock price must rise above INR 300 before the call option is worth anything; furthermore, because the contract is INR 10 per share, the break-even price would be INR 310(INR 300 + INR 10).
As shown above, a long options trade has unlimited profit potential, and limited risk, but a short options trade has limited profit potential and unlimited risk. However, this is not a complete risk analysis, and in reality, short options trades have no more risk than individual stock trades (and actually have less risk than buy and hold stock trades).
In terms of valuing option contracts, it is essentially all about determining the probabilities of future price events. The more likely something is to occur, the more expensive an option would be that profits from that event. For instance, a call value goes up as the stock (underlying) goes up. This is the key to understanding the relative value of options.
Covered calls can make you money when the stock price increases or stays pretty constant over the time of the option contract. However, you could lose money with this kind of trade if the stock price falls too much (but can actually still make money if it only falls a little bit). But by using this strategy, you are actually protecting your investment from decreases in share price while giving yourself the opportunity to make money while the stock price is flat. 
A longer expiration is also useful because the option can retain time value, even if the stock trades below the strike price. An option’s time value decays as expiration approaches, and options buyers don’t want to watch their purchased options decline in value, potentially expiring worthless if the stock finishes below the strike price. If a trade has gone against them, they can usually still sell any time value remaining on the option — and this is more likely if the option contract is longer.
For example: Tomatoes are cheap in July and will be expensive in January, you can’t buy them in July and take delivery in January, since they will spoil before you can take advantage of January’s high prices. The July price will reflect tomato supply and demand in July. The forward price for January will reflect the market’s expectations of supply and demand in January. July tomatoes are effectively a different commodity from January tomatoes.
When buying or selling options, the investor or trader has the right to exercise that option at any point up until the expiration date - so simply buying or selling an option doesn't mean you actually have to exercise it at the buy/sell point. Because of this system, options are considered derivative securities - which means their price is derived from something else (in this case, from the value of assets like the market, securities or other underlying instruments). For this reason, options are often considered less risky than stocks (if used correctly).