Most important when trading is to make sure your balance will not go into negative. In fact trading is risky and that is why having a reliable broker is obligatory.
For my broker, ActivTrades, the interests of clients are main objective, which is why it is offering its clients Negative Balance Protection.
Your account has a trade out level which is put in place to ensure you do not lose more money than your deposit. ActivTrades also offers the Balance Protection Policy and will credit your account to a zero balance if your account goes into negative as a result of trading activity.
The Balance Protection Policy applies across multiple accounts, so if you have a negative balance in your account and a credit balance in your second account then the credit balance will be used to offset the negative balance. This option applies to joint accounts too, as each joint account holder will be responsible for a debit or credit available equally.
The balance protection is open to all retail clients.