The usual ratio of exchange market leverage is 100:1. In this case in order to buy for example $10,000, you have to pay $100 to start the trade, as you effectively borrow the remaining $9,900.
Even the most trivial movements in the value of a currency can become a reason of incredible gains and unpleasant losses.
In order to escape losses you should study the main rules of risk management, learn how to set stop-loss and stop-limit orders.
You should devote most of your time on learning about trading plans, money management, position sizing, technical and fundamental analysis, as well as develop a good trading strategy before starting your trade.
One of the utmost important factors that you should bear in mind is that foreign exchange trading contains a high level of risk, and hence, is not suitable for all investors.
The high degree of leverage contains high level of risk, as if you earn relatively huge amount, in the same way you can lose more than your initial deposit.
From the above mentioned features it follows that before trading you should carefully think over risks and inherent costs as well as ask for advice if necessary.