If you want to build enough wealth to become financially independent, you probably already know you should be investing. But what, exactly, should you be investing in? You can use an investment vehicle like a Roth IRA or a 401(k) to gain tax advantages for the money you put away, but you'll still have to make a choice of investments to build and maintain enough wealth to sustain yourself for the indefinite future.

So which assets are most important?

1. Stocks

Stocks are one of the most common and most approachable investment assets. Each share of stock represents fractional ownership of a publicly-traded company, and the price of a stock fluctuates as opinions of the company's earning potential change. In general and over a long period of time, the stock market tends to rise in price at a fairly consistent rate (with occasional years of disarray). Stocks do carry some inherent risk, but as long as you purchase and hold stocks from multiple different companies in multiple different industries, and hold those stocks for many years, those risks will almost certainly be mitigated.

If you're aiming to build wealth, you may consider targeting small- to mid-cap stocks, which are just emerging and tend to be priced lower than their large-cap contemporaries. These stocks are riskier, since they haven't proven themselves, but they also have high potential for growth. If you're aiming to preserve or collect your wealth, you might target stocks that pay high dividends--these are essentially distributions of profits to shareholders, and some major companies will pay 2 to 4 percent annually. That means for every million dollars you have invested, you could skim $20,000 to $40,000 a year off the top without touching your principal.

No matter what type of stocks you buy, you'll need to do research on each company to learn its strengths and weaknesses and evaluate the "fairness" of the current price.

2. Futures

If you're feeling more adventurous, you could try trading Nasdaq futures (or other futures contracts). A futures contract is basically an agreement to buy or sell a specific asset in the future, at a specified date and price.

You can trade almost anything this way, including stocks and commodities like sugar. The idea here is to make a guess about how the price of an asset will change, and capitalize on that predicted change. For example, if you believe the price of an asset is about to plummet, you could sell a contract to sell the price in the near future at its current price, netting you a profit if the price drop unfolds.

Futures are inherently riskier, especially if you don't have much experience. However, they can be a fast way to build wealth.

3. ETFs and Mutual Funds

ETFs and mutual funds are both ways to invest your money in a large collection of stocks (and other assets) at once. Mutual funds tend to be actively managed, which means someone's in charge of overseeing the asset distribution and changing it to maximize profit; because of this, they tend to charge fees for investing in them.

ETFs (exchange traded funds) work more like stocks, with low or nonexistent fees, and allow you to invest in many assets simultaneously. They're both good ways to invest in the stock market without exposing yourself to much risk.

4. Bonds

Bonds are essentially loans of money to a company, organization, or governmental body. Usually, you'll buy bonds for a fixed price, and with a fixed rate of return (like 2 percent) and duration (like 2 years). If you buy bonds from a reputable organization with significant trust and a long history, they're an incredibly safe investment.

The flip side is, they won't give you nearly as much of a return as stocks. They're best used as a way to mitigate risk, and keep portions of your portfolio safe.

5. Real Estate

You can also invest in real estate, either by buying property you believe will appreciate in value over time or by buying a property that allows you to collect more in rent than you'll pay in upkeep (and on your loans). Real estate is a mixed bag; if you're experienced, and make wise purchasing decisions, it can be a savvy investment and a source of steady, predictable income.

However, if you try to flip houses or depend too much on upward momentum in the market, you could also lose a lot of money. Make sure you work with experts and dedicate time to improving your skills.

Bottom-Line Tips

If you feel overwhelmed by the sheer number of options available to you, take things one step at a time. Your first step should be coming up with a financial plan that allows you to put money away for investing on a consistent basis. Then, you'll want to open an investment account and start squirreling money into it.

No single asset is enough to guarantee you a path toward wealth, or preserve all your savings when you get there--that's why it's important to diversify and actively manage your portfolio--but at the same time, you can make investing more approachable by focusing on learning one asset at a time. Start with the asset you feel most comfortable with, then branch out to learn other assets to add to your portfolio.