The strike price is how much you'll have to pay to get your stock. It's set at the time stock is granted, you should ask what it is. You don't always spend the strike price, because sometimes it winds up being higher than the stock price. The discretion factor ranges from zero for 'mars or bust' investments to one for shares of bundles of cash. An option's value isn't based on upside potential, it's based on average expected money you can get from it.
Greater risk makes it worth less.
The risk factor varies from zero if you're just barely going to be able to retire some day to one if you're already set for life and the rest is gravy. Liquidity factor varies between zero if you're on the verge of not being able to make mortgage payments to one if you should be saving more anyway. You should view this as possible insider information. Often it's bullshit, but some people really have gotten rich this way. If you become rich on paper from options, remember that it's all funny money until it vests - your paper fortune could evaporate just as quickly as it appeared.