Whether you start with a little money or lot, you can choose from a wide range of investments both in the US and around the world. You can buy stocks from Hong Kong market, future from Singapore market. What you decide to do depends on your goals, the amount you have to invest, and your willingness to take risks. Knowing what to choose and when to choose it is the key to sound investing.
Selecting the right investment will depend on your personal circumstances as well as general market conditions. The 'Right' investment is a balance of three things: liquidity, safety, and return.
Liquidity - How easily the money can be converted to cash?
Safety - What's the risk involved? Stock in SP 500 and in big company with a long history of profitibility is considered fairly safe.
Return - What can you expect to earn? Safe investments promise a specific though limited, return. Others often the opportunity to make - or lose - a lot. The kind of investments you make, the amount you can afford to invest, and the degree of risk you are willing to take will all determine your return.