Before making the decision to purchase ETFs, you should first determine your investing goals, your ideal asset allocation, and the types of ETFs you want to purchase. Then you can develop your investing budget to determine how much you have to invest, including the expenses associated with managing ETFs. Once all that groundwork is done, low-cost, commission-free ETFs become a very attractive tool because of their ability to deliver diversification through a single investment.  Commission-free means that whenever you buy or sell shares of an ETF, you don’t pay any trading fees. However, there are still other costs associated with commission-free ETFs such as the operating expense ratio (OER). The OER is the percentage taken from the fund annually to pay for the fund’s expenses. For example, if you have $5,000 in an ETF with a 0.3% OER, your expense is $15 a year. A good rule of thumb is to look for ETFs with an OER that doesn’t exceed 1%. Commission-free ETFs are also a good idea if you trade frequently and you want to save money on overall investing costs.