Penny stock investing doesn't have to be a crap shoot on long-shot stocks. Done well, penny stocks can be a great way to diversify your portfolio and really amp up your investment profits. While penny stock investing can be risky, it can also be very rewarding.

I recommend finding bargain penny stocks traded on major exchanges, for no less than $1 a share and with a proven track record. These penny stock investments should show significant earnings growth and strong buying pressure behind shares, increasing the likelihood that these stocks will be on the way up in the very near future.

When it comes to buying inexpensive stocks, sometimes investors think that they can find bargains for just a few dollars a share. Sometimes they are right -- but other times these penny stocks can expose your portfolio to big risk and lose you a bundle in a hurry. Here are five popular stocks under $2 a share you should avoid like the plague.

Penny stock investing tends to be riskier than investing in large cap stocks, but that doesn't mean you have to settle for losers in your quest for big penny stocks that take off. Here are five penny stock losers to avoid:

Rival home improvement chains Home Depot Inc. (NYSE: HD) and Lowe's Companies Inc. (NYSE: LOW) are scheduled to report quarterly results this week. Not surprisingly, given the ongoing housing slump, analysts surveyed by Thomson Financial on average expect both companies to post earnings lower than in the same period a year ago. For Home Depot, that's 61 cents per share, down 20.8%, and for Lowe's, 56 cents per share, down 16.4%. Meanwhile, cabinet maker American Woodmark Corp. (NASDAQ: AMWD), for whom Home Depot and Lowe's are major distributors, is also expected to report lower earnings: 11 cents per share, down 67.6%.

The presidential campaigns have prompted much discussion of energy policy and alternative energy sources. Some solar-energy-related concerns are scheduled to report this week, and expectations seem to be high. Trina Solar Ltd. (NYSE: TSL) is expected to report 81 cents per share earnings, up 67.9%; ReneSola Ltd. (NYSE: SOL) is expected to post earnings of 32 cents per share, up 62.5%; and Suntech Power Holdings Co. (NYSE: STP) is expected to have earnings of 32 cents per share, up 21.9%. Even China Sunergy Co. Ltd. (NASDAQ: CSUN) is expected to have swung to a profit of 3 cents per share, from a per-share loss of 14 cents a year ago.