Greg has a lot of great advice, especially about diversity. Don't put all your eggs in one basket. Also, if you prefer to not look at individual stocks, you can do just as well with a good mix of GOOD mutual funds. Here is as good a list as I've found and what I chose from:
http://money.cnn.com/magazines/money...nds/index.html
If you just picked a mix of these funds and did no more research and bought them through a Schwab, eTrade, etc. and rebalanced every year at tax time you'd be doing pretty well.