Day Trading

1) Get cash up front.
2) Will make money beyond the cash you get up front if the option is actually excercised (assuming the strike price of the option you sell is greater than the current price of the stock your selling.)
3) Aren't taking any big risks that you wouldn't be taking anyway by holding the stock.

Of course you risk making less money that you'd otherwise make if you simply held the stock and it goes well above the strike price. But most options expire worthless, and quite a few of the ones that don't probably still don't make enough to cover the contract price (ie your still better off).

How much you can make doing this depends on the stocks you invest in and the manner in which you do it. Not shockingly people are willing to pay more for options on a hot growth stock like Apple (a Sept 140 call contract trades for $420, slightly more than a 3% yield) than they are for a value stock like Walmart (a Sept 45 trades at $45, a 1% yield). Also the closer the strike price is to the stock's current price the more its worth but the more likely it is that the contract will be excercised (an Apple Sept 140 contract is worth $420, a 150 is worth $140, a 160 $45, etc). I generally sell contracts that are short term and fairly far out of the money (as far as I can go while still making a decent return).

Okay, that was a lot…

Buying calls or puts is obviously far riskier. My advice would be that you should only buy options rarely, if at all, and look for options that don't expire for at least a year (more time is relatively cheap when buying options–the first month is the most expensive, as is the first year, etc).

And to answer your originial question– unless you are VERY lucky (and have taken a huge amount of risk) I doubt you could make a living in the short term off of options. But you should be able to augment your returns by selling calls and over the long term that can help the 20k grow.

Good luck.