Make sure that you fully understand how a margin account works. If you don't, limit your investments to a cash account where you must pay for the securities in full. Cash accounts are not subject to margin calls. Know your firm's margin policies. Speak with your broker or check the firm's Web Site for any changes in margin policies.
Firms can make changes at their discretion, and are more likely to do so in volatile markets.
If you use a margin account, make sure you don't use all of your available funds to trade securities in the margin account. Manage your margin account. If you see that the securities in your margin account are declining in value, deposit additional funds in your account. These cash deposits will reduce your loan and lessen your chances of a margin call, as long as the value of the securities in your account do not continue to decline or you don't use the money to engage in even more securities transactions. This firm and NASD Regulation, Inc. are excellent sources of information on margin accounts.