There's one special note for South African traders. For some reason beyond any rational explanation, I've heard that PayPal lets people in South Africa send money, but not receive it. Brokers often like to send withdrawals by the same method that deposits were made. In cases like this, getting your money back can be challenging.
So, if you are in any country that doesn't let you get money by PayPal, I'd recommend not using PayPal to fund your account.