With a broad-based investing strategy, you don't necessarily have to look for sectors that will outperform the overall market. But if you're willing to take the additional risk that comes from making a concentrated investment in a particular sector, there are a number of ways to do it.

For instance, amid all the news about struggling automakers, up-and-down financials, and an economy that's still trying to hit bottom, you may not have noticed that the bust in energy appears to have run its course. But with energy prices starting to head back up, you won't be able to ignore what's going on in the oil patch much longer.

Quietly, things are looking up for energy companies. Gasoline recently rose beyond $2 per gallon on average, while oil prices have moved convincingly past the $50-per-barrel mark in recent weeks.

If you want to take advantage of this possible trend shift, you'll find a number of ways to participate. Which one's best for you?

Mix and match
Perhaps the most obvious way to try to profit from a coming oil boom is to buy shares of a few individual companies in the industry. But higher energy prices don't necessarily affect every energy company in the same way. While oil producers like BP (NYSE: BP) benefit directly from rising prices, refiners like Valero Energy (NYSE: VLO) can actually get hurt by higher oil if prices on refined products like heating oil and gasoline don't follow suit.

Because of the dangers of picking individual companies, you may want to make a more diversified investment in energy. Here, too, you have a number of choices.

1. Energy sector funds and ETFs
To get stock exposure in companies throughout the energy industry, ETFs and sector funds are perhaps the most efficient method available. The Energy Select SPDR , for instance, includes big players like ExxonMobil (NYSE: XOM), along with gas producer Chesapeake Energy (NYSE: CHK) and coal miner Peabody Energy (NYSE: BTU). With an expense ratio of just 0.22%, costs won't take a deep bite into your returns.

Similarly, conventional sector mutual funds like Vanguard Energy also provide a low-cost entry into the industry. Although each fund takes a slightly different angle on how it allocates money among different stocks, you can generally count on seeing your investment move in line with the overall energy sector. Being cost-conscious is critical, though, to eke out the best returns.

2. Closed-end funds
Less well-known are energy closed-end funds, which span a wider range of energy-related investments. Some closed-ends, such as Tortoise North American Energy , own a number of limited partnership investments. Others, like Petroleum & Resources , stick with top stocks like Chevron (NYSE: CVX) and Occidental Petroleum (NYSE: OXY).

The benefit of closed-end funds is that you can sometimes pick up shares at a discount to net asset value. Petroleum & Resources, for instance, currently trades at about a 12% discount, meaning you're paying only $0.88 for each dollar's worth of the fund's holdings. Continued...