How can you avoid this unanticipated surprise? Margin calls can be effectively avoided by carefully monitoring your account balance on a regular basis, and by using stop-loss orders on every position to minimise the risk. Another smart action to consider is to implement risk management within your trading. By managing your the potential risks effectively, you will be more aware of them, and you should also be able to anticipate them and potentially avoid them altogether.
I post this to let you know, as the title mentions it, that I made a trading diary, with google documents tool. This a generic spreadsheet which allows any trader to manage his trading (his risk, his pnl, his opened position, the orders...) with a trding diary. Every trader,should have one, and I mad mine with google docs. At least you must have an account to acces this spreadsheet.