Investing in the stock market is the common knowledge place to go for good growth on your retirement savings. When you're first starting to invest it's easy to feel like you can't afford to invest or you don't have enough money to make any difference. Here are a couple of points you should look at before you begin your investing career.

1. Are you debt free?If you are not debt free then the interest you are paying on your debt will likely outweigh any average stock market returns. Not to mention the risk of not being able to pay your debt far outweighs a few extra percentage points return on your investment. Other than your mortgage I would invest a dollar until I was debt free.
2. Will commissions kill you? You don't want to pay more than 2% of your investment in commissions. If you're investing in a retirement account to mutual funds this probably won't be an issue. If you're investing in single stocks you need to look at the fee schedule. If you're paying $7 per trade, that's $14 per buy and sell. That's 2% of $2800. So if the amount you have to invest is less than $2800 I wouldn't consider buying unless you plan on holding the stock for a very long time. If you're planning on investing in more volatile stocks you should consider the buy/ask spread also. If you can buy a stock for $5, but could only immediately sell it again for $4.5 this is called the spread, which in this case is 50 cents. 50 cents of $5 is 1%, so you only have 1% of commissions left to work with.
3. Will I be diversified? If you only have enough money to purchase one stock, you should consider saving your money or purchasing diversified mutual funds instead. Until you can afford at least 5 different stocks I wouldn't invest on my own. If you own a mutual fund and wish to purchase a single stock with separate funds, that would be acceptable also.

I want you to invest for you future, I just don't want the institutions siphoning all of your money before you can enjoy it. All good things are worth waiting for.