Some investments pay out earnings on a regular (quarterly, monthly, or annual) basis, while others pay out earnings at the end of the investment period or may have age requirements for when you can withdraw your money without a penalty. Make sure your investment income stream matches your investment timeline.
You should also consider the tax ramifications. If you are saving for retirement or for education, consider investments that offer incentives for saving for a particular purpose. Your contributions for some investments are tax deductible, but the earnings are not taxed (e.g. Roth IRA); your contributions to other investments may not be taxed, but the earnings are taxed (e.g. traditional IRA).
You don’t have to put all of your money in one investment. Consider diversifying your investment portfolio by placing your money in several investment vehicles. This can protect you from risk; while one of your investments may be performing poorly, another one of your investments can make up for those losses.