Visit a reputable OSRS Gold website such as RSorder for a way to be sure you'll receive your gold. Since they're a highly experienced website that has been trading since 1999 and are familiar with the industry inside and out, they are able to protect trades.
They have great security measures in place to avoid fraud. They also have an escrow service that's modeled on PlayerGuardian in order to make sure the RS 07 gold bought through their website is sent to purchasers.