Even though your a Yankee fan I'll answer your question......When you transfer you may want to get a paypal payment up front because once you transfer those points there not coming back for a non payment. Once you get that payment call MS and make the transfer. Some like to have a conference call when this transaction occurs. It is an easy process that takes little time.
The most common way is 50% paid pretransfer 50% as soon as the transfer is confirmed, that way neither party has more than 50% at risk. Paypal is helpful also, although if you read the fine print since it is not a physically delivered item the protection is limited.