I'm 23. I have $3000. How can I best use it to make more money?

As others have pointed out, obtaining a 12% after tax return is not something you can count on no matter how you put the money to use. As you've pointed out CDs will produce a negligible return and also come with liquidity restrictions. Investing in stocks (bonds are not an option to beat a 12% after tax rate of return) will not produce that kind of return without you taking on a severe level of risk.

It's hard to give a good answer without knowing what kind of income you have and how regular a source it is. The more regular your income, the more aggressive you can be paying down your credit card debt. But if you expect to go a while without a significant source of income, you will need to keep more cash on hand.

You could ask family or close friends for a no-interest loan to help you get your credit card debt down to $3000 or lower. Depending on how much they are willing to loan you, you might be able to use some of your cash to pay it off completely.

The bottom line is that, realistically speaking, you are not going to be able to "snowball" $3000 into anything when you owe $6000. Your snowball needs to be pushed uphill right now (pardon the mixed metaphor). When you get over that hill you can start thinking about rolling it down the other side.

In the meantime, you can do as Mr. Kaufman suggested and spend a small amount on educational books that will prepare you for the day when you are in the black.

Consider the mathematically equivalent scenario: if he had only $3k in CC debt, would you recommend putting $3k more on the card for books and training?

With $30 and craigslist I bought my first smart phone, rooted it and sold it for $50. Then I bought another, learned how to root it and sold that one for twice what I bought it for. In the end, I made $100 excluding the two smart phones I currently own that were purchased with the profit. And all this occurred within a month or two. It took a couple of hours, but now, for a fee, whenever someone has a problem with their phone they come to me.

But with $3000 I recommend using most of it to pay off your debt, and take a night to analyze where all your cash is going and how you ended up with so much debt! It would be best if you could provide additional information such as your monthly salary and expenses, and maybe others can give you advice on how to cut back and live happier!

Absolutely. If you're able to take a one-time $1-3k expense and turn it into a $10k+ annual increase in salary / profit, that's a huge win. In my experience, the actual returns are much, much higher than $10k/yr for pretty much everyone who's willing to invest the effort.

Most of my early book / course purchases were financed with credit card debt. I paid off my cards in full with a small portion of my first product launch. I'd do the same thing in a heartbeat.

Unlike the OP, I have no debt and $6000 in the bank. A soon-to-be grad student, I'm also looking at a pretty low income for years to come. So I'd like to be able to reasonably quickly free up my assets. Is the money still best left in the bank?