Find a reliable RS Gold site such as RSorder for a way to be sure that you'll receive your gold. Since they're a highly experienced website that has been trading since 1999 and knows the business from the inside out, they are able to protect trades.
They have great security precautions in place to stop fraud. They also have an escrow service that's modeled as PlayerGuardian for ensuring that OSRS Gold For Sale purchased through their website is distributed to purchasers.