When choosing an option, for me it is about the risk/reward. The main things I look at are: Delta, Implied volatility, volume/open interest and theta if I am holding it overnight. If swinging overnight I usually look for 0.30 delta or more. 0.25 or more is fine for daytrades. The difference between those 2 options, would be that since one is further out of the money (217.50), the profit potential percent wise would be higher if TSLA was to have a significant move to the downside over the 220 put because you are making a technically more risky call. Implied volatility is tough to gauge because it varies on each stock, but I usually say anything from 10-60% is low, 61-99% is middle, and 100 or higher is in the high range. Basically the higher the implied volatility, the more inflated the premium is, and the possibility that it will decrease. When IV decreases while you are in the contract, you could end up in one of those situations when the stock goes the way you want, but you still somehow are down on the contract.
