If you're buying young, go aggressive and let the money sit. You will tend to be antsy and want to buy/sell, but that's not the goal. This is money you're putting away for a later date.
By being aggressive it means you take a slightly higher risk, but you also take a large profit. If you go with something that is growth oriented, you might just get dividends or something small. If you don't have a lot of money, go big. If you do, you can afford to go with a growth.
If you buy 100 shares at $100 and it drops to $10, you still have 100 shares. It can go up, it can go down. Watch the market and get an idea of what the indicators are for your market.
I have everything highly aggressive. When I used a stock broker, the told me to expect about 7% a year. I pulled my last quarter's 401k that I hand selected myself after about 15 hours of research. In a single quarter I had pulled an unheard of 77% gain. I had like $16,000 in my 401k and 3 months later I had over $30k. They were amazed and obviously didn't beleive me.
Find, watch, invest.
Ford and Lazy boy are good investments. Anderson's (bio fuels, midwest supply company) is good but pricey.
For you, I'd stick to stocks under $10 so you can buy enough shares. It doesn't matter how much you invest if you don't have enough shares.
My 401k looks at a lot of small cap stocks, equitity holding firms, and highly aggressive funds. I avoid bonds and the money market since the pay out is low for the risk invested.