There are two basic ways you can increase the ROI of your investments. You can find a winning strategy to increase your returns, and you can reduce the amount that is paid out of your funds. Market performance is unpredictable, but the costs of investing are knowable and within your control. Controlling the known variable of investment cost just makes sense. To keep your costs down, look carefully not only at the fees associated with your investments, but also at the tax liability to which they expose you.