A complete answer to your questions is hard to provide here. A few things to think about
You need to take on more risk today to have a shot at 8-10% than you did at any time in the past 50 years. If by cash you mean the U.S. dollar, it's a commodity that doesn't provide a very good risk/return potential. If by stocks you mean the US equities markets, you have only to look at their performance over the past 10 years to know that 10% a year is a dream at this point. I do not see the US equities markets providing anywhere near 10% on an inflation adjusted basis going forward, and please remember that your real return must always be thought of in inflation adjusted terms. I do not and will not hold any U.S. dollars as I feel that even without another round of QE, the currency will not perform very well.
The idea of throwing your money into bonds and 'waiting this thing out' is appealing, but obviously you are not going to achieve your returns and the fact is that we do not know how long 'this thing' is going to last. What Swag22 said has some merit, but you don't have to hold US Treasuries, you can hold other government bonds.
Someone else said 'buy when blood is running in the streets'. This is a very good idea. However, blood is not running in the streets yet, not by a long shot. See below - I'm not saying that you shouldn't buy selected equities, just that blood is not running in the streets.
If you do not have the time and inclination to do a lot of research, there is not much you can do except to limit your stock market exposure to established stocks which throw off dividends. The value of dividends is vastly underestimated by people whose knowledge of the markets is incomplete. By all means, open a self-directed account and do not pay a 'professional' to do what you can do yourself.
The best thing for you to do is to start the process of educating yourself about the markets. If you are in your mid-twenties, this process will yield a way bigger return than your 15K. One of the best ways to achieve decent risk adjusted returns is to do what Warren Buffet did (in part). Yes, it still works. Look for small-mid cap companies with room to grow and invest in them for the long term. If you ask 'how do I do this' it's too big a question. You have to get out there and learn.
Someone said buy gold to get your returns. I can tell you this. Gold will trade at $1500/oz in the future. Anyone with the cajones to short it is going to make a hell of a lot of money. I wanted to short it at $1600 but one look at the chart showed me that it would be a bad idea. I am not telling you to short gold, I am just saying that anyone who shorts it here will eventually make a nice return. There are big risks associated with this type of position, including the risk that you could be right and still lose more than your investment.
Most important thing for you is this - don't be one of the sheep. Learn how the game is played and play it for yourself. Most guys think that their 'investment advisor' is a guy who has some sort of special ability to make good picks or grow money. This is usually a load of crap. Not always, but usually. Most investment advisors, especially those working for the bigger firms, are working from a fixed playbook and are not making any creative decisions at all. You can get the playbook and do what they are doing without paying them their edge.
Edited by tradernick - 9/9/11 at 3:15am