Safe ways to pay
The best way to pay for something online is via PayPal. The reason this is so safe is because PayPal is an independent third party who transfers funds from the buyer to the seller, and there's an electronic paper trail left if something goes wrong.
If the seller has the facility to accept credit cards, this can also be a safe way to pay as you can contact your card issuer and initiate a chargeback if the item you pay for doesn't arrive.
Another good way of paying if the seller agrees is to use a trusted escrow service such as escrow.com. An escrow service works as a third party and does not transfer your payment to the seller until the item has been received.
1.) Is sending a payment via an escrow service safe?
2.) Is sending a payment via Western Union safe?