by John Summa (Contact Author  Biography)
Greeks play a critical role in strategy behavior, most importantly in determining the prospects for success or failure. The key Greek risk factors  Delta, Vega, and Theta  were explained both in terms of how each relates to options in general (i.e., What is the sign on the Delta of all call or put options, or what is sign on the Theta of a call or put option?). While Deltas of calls are always positive and Delta of puts always negative, for the other Greeks the signs for puts and calls are the same.
Theta is negative for all options because whether puts or calls, each tick of the clock reduces premium on an option, other things remaining the same. Likewise, all options have positive Vega values, since regardless of whether call or put, a rise in volatility will add value, while a decline will take value away. When moving to the level of position Greeks (i.e., Which strategy is employed and which strategy Greeks are associated with it?), the picture gets more complicated.
Calls and puts can have either negative or positive Greeks depending on whether or not they are short (sold) or long (purchased). And a combination of options (calls and puts or different strikes using calls or puts) will result in a position Delta, Vega or Theta depending on the net position Greeks in the strategy.
Finally, in the last part of this tutorial, the ceteris paribus assumption (all things remaining the same) is dropped to look at how Greeks change when other things don't remain the same, such as implied volatility (IV) and time remaining to expiration. While just one avenue for exploration, it was shown how Delta changes with both changes in time remaining until expiration and falling levels of IV. Further simulations along these lines could have been carried out, but due to the limitation of space it is not possible here.
Suffice it to say that a rise in implied volatility will have the reverse impact in similar magnitudes for calls and puts. As for other scenarios, it would be best to acquire some software or access to a sophisticated broker platform that allows for extending this type of multidimensional analysis to other strategies.
For now, bear in mind that each strategy will be impacted by changing levels of implied volatility (which can hurt or help depending on the sign and size of the position Vega), time remaining to expiration (position Theta risk), and to a smaller extent interest rates (typically negligible for most short to mediumterm strategies).
With enough practice, eventually an understanding of the relationships of the Greeks to each strategy will become second nature so that analysis only becomes necessary to calculate their exact magnitude if using large lot sizes.
Remember, it is better to trade smart. Begin slowly, risking little, and eventually increase risk when you begin to achieve success on small positions.

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The Forex Greeks And Strategies
We look at the different kinds of Greeks and how they can improve your forex trading. 
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Measuring Options With the Greeks
Delta, gamma, theta and vega are “the Greeks,” and they provide a way to measure the sensitivity of an option’s price. 
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Understanding Theta
In options trading, theta measures the daily rate of decline in an option’s value as it nears its expiration date. 
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Options Trading Strategies: Understanding Position Delta
Learn more about the position delta hedge ratio and how it can tell you the number of contracts needed to hedge a position in the underlying asset.