As the buyer of an option contract, you’re concerned with only two things.  First is which direction you anticipate the underlying stock to move and second is now likely the stock is to make enough of a move for you to earn your anticipated profit on the trade.

The first question of the direction of price movement determines which type of option contract, put or call, that you’ll buy.  A call option lets you buy at a strike price that’s currently higher than the stock’s market price so buy a call if you expect the stock price to rise.  A put option lets you sell at a strike price that’s currently lower than market price so buy a put option if you expect a decline in share value.

As for the question of how likely the stock is to make enough of a price movement for you to show profit … that’s a little more complicated.

Premium Value
In general, the higher the premium you have to pay for an option contract the greater the potential that the option contract will eventually become profitable.  Premium value increases as the share price gets closer to the strike price but decreases as the option contract gets closer to its expiration date as fewer days until expiration means fewer days for the underlying stock to show appreciable price movements.

Volatility of the Underlying Stock
A stock whose price is more volatile is also more likely to show the sudden moves that turn an unprofitable options contract into a profitable one by driving share price past strike price.  This volatility is also reflected in the premium value, though, as a more volatile stock has more potential to become profitable late in the contract with a sudden unexpected price move.

Thus, the premium for more volatile stocks tend to stand up better to the test of time when compared to less volatile stocks to account for this increased probability of more drastic price movements.  But, those movements could also happen in the opposite direction making the contract more potentially risky as well.

Belief
Underlying the market value of the option contract itself, though, is your belief about how likely the stock it represents is going to move substantially enough for you to profit by buying the contract.  That question and the different answers different traders with different goals, beliefs, and risk tolerances have when asked it is what makes the market for options exist in the first place.

If the current market price of the option represented a precisely quantified value of its worth then the opportunity for traders to profit from options would be eliminated.  It’s the very fact that different people have different opinions about whether an option contract is undervalued, fairly valued, or overvalued that create opportunities for profit for everyone involved.

So, in the end, option valuation is a personal decision based on your own research into the volatility and value of the underlying stock and what that knowledge and your trading experience tell you is most likely to happen to the stock’s price.  If you’re right you profit and if you’re wrong you don’t but the nice thing about options is that, when buying, you’ll never lose more than the premium you paid.  That makes being wrong quite a bit less painful than being wrong in other forms of investing.