When buying a call option, the strike price of an option for a stock, for example, will be determined based on the current price of that stock. For example, if a share of a given stock (like Amazon (AMZN) ) is $1,748, any strike price (price of the call option) that is above that share price is considered to be "out of the money." Conversely, if the strike price is under the current share price of the stock, it's considered "in the money." 
Still other traders can make the mistake of thinking that cheaper is better. For options, this isn't necessarily true. The cheaper an option's premium is, the more "out of the money" the option typically is, which can be a riskier investment with less profit potential if it goes wrong. Buying "out of the money" call or put options means you want the underlying security to drastically change in value, which isn't always predictable. 
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. 
Volatility: If an options market is highly volatile (i.e. if its daily price range is large), the premium will be higher, because the option has the potential to make more profit for the buyer. Conversely, if an options market is not volatile (i.e. if its daily price range is small), the premium will be lower. An options market's volatility is calculated using its long-term price range, its recent price range, and its expected price range before its expiration date, using various volatility pricing models.
The fee you are paying to buy the call option is called the premium (it's essentially the cost of buying the contract which will allow you to eventually buy the stock or security). In this sense, the premium of the call option is sort of like a down-payment like you would place on a house or car. When purchasing a call option, you agree with the seller on a strike price and are given the option to buy the security at a predetermined price (which doesn't change until the contract expires).